13 ms·

We migrated our PostgreSQL database with 11 seconds downtime

• Edwinr95 3y ago
  I'm quite negatively surprised that a government service is moving from their own platform to AWS for such an important service.
  • cpursley 3y ago
    And an American one, at that (we’re talking government services here, not some SaaS). Are there really no native UK cloud providers?
    • cameronh90 3y ago
      Not any remotely comparable. The small “cloud” providers we do have were just reselling vSphere last time I looked into it.
  • jazzyjackson 3y ago
    I don't know what it's like in UK but it may be the case that government has a hard time a{ttract,fford}ing talent to administer everything in house. Not that AWS is great for cost saving but if its between paying 50k/year for cloud services and not being able to find an engineer who will competently do the job for less than 50k, then the cloud is your only move really.
    • swozey 3y ago
      They require various clearances (digging into your life and past relationships to a miserable degree), don't allow someone to have ever smoked pot and pay half or less of what you can make in the pvt sector here (usa). Everyone I know working FedRAMP jobs is prior military/g-level.
      • robertlagrant 3y ago
        They wouldn't need that. And having been SC cleared in the UK, and known a few DV-cleared ones, at least in the UK they don't care if you've smoked pot. They just care that if you have, that you don't mind your family knowing one day. They don't want people who can be blackmailed.
        • swozey 3y ago
          Here it's like this: Don't ever lie to them, "no matter what it is they'll find out." So, some people don't lie, say they smoked pot in high school and none of them make it to the next step. I had a twitter convo last year or pre-x whenever with the CTO of some org I can't remember (I don't think centcom, something much smaller) and he mentioned that they've lightened up quite a bit, or at least his program which was a softwar engineering group was more lenient. He was looking for engineers on via twitter on his official account. So maybe that's loosening up here thankfully.
      • deleted 3y ago
        [deleted]
    • justsomehnguy 3y ago
      > who will competently do the job for less than 50k, then the cloud is your only move really Well, there is the other way, but, as we know, never ever that would happen.
    • prmoustache 3y ago
      Once your past the emerging startup status, running on the cloud involve as much engineers and complexity as running on prem if you want to follow best practices. The "let's be managed and only hire developers" is a huge myth. All large organizations involve tons of "cloud engineers" or "devops" depending on how they want to call them and are just sysadmins with a different name and a bigger paycheck. Having actual datacenters doesn't add a ton of complexity and datacenters themselves are often managed by people who don't even have an engineer paycheck. The main difference between being on prem vs cloud is you have to plan (how many servers/storage/network equipment you have to buy and replace on the following year) and pay for stuff (like space, racks) more in advance + take into accounts delays in delivery. This is where cloud makes the job much faster for companies but given the slow pace at which gov stuff happen usually I don't think this is a problem for them.
    • solatic 3y ago
      > and not being able to find an engineer Remember it's not just about being able to find one single engineer - then they become key-person risk. You need multiple engineers to be able to handle the loss of that engineer, either temporarily (vacation) or permanently (suddenly hit by a bus). Then you end up having a team of DBAs. Then you have functional rather than feature teams. Then you need multiple managers to align to get anything done, and have internal politics. Being able to consume databases as a product has non-trivial value.
  • ris 3y ago
    GOV.UK PaaS also runs on AWS (for as long as it remains to exist)
  • okasaki 3y ago
    All UK businesses run on Oracle and Microsoft, so I'm not sure why you're surprised. They have us by the balls.
  • kingkongjaffa 3y ago
    > This is an AWS RDS PostgreSQL database and it lives in the PaaS’ AWS account. Our apps that run in the PaaS talk to this database. We are going to call this database our ‘source database’. It already was. Read the article.
  • conception 3y ago
    AWS has a lot of pre-audited compliance built into their services. Being able to inherit their certification for services can save an organization a lot of time and effort.
    • lnxg33k1 3y ago
      Its not an organisation, its a blucking government, it handles citizen data, and its sending them to a company of foreign country, because it can’t hire some system administrators? A GOVERNMENT? What are they doing? Still looking for their product market fit and can’t afford the headcount? Is it a joke? EDIT If they are looking for money id like to participate a bit in the seed round
      • kunwon1 3y ago
        AWS has a G-Cloud for UK just like they have one for US, no?
        • snoman 3y ago
          AWS has government specific regions (called GovCloud). Many services or features make it to GovCloud later than other regions because of the certification requirements.
        • travem 3y ago
          AWS has US based GovCloud regions: AWS GovCloud (US-East) and AWS GovCloud (US-West). It does not have a UK specific GovCloud region that I am aware of.
        • bboygravity 3y ago
          Why can't the UK government build there own cloud? It's just completely insane to me that they would make the gov internet infrastructure completely (geopolitically) dependent on another country AND just literally give all their (citizens') data away AND pay for that "privilege"?! I mean if the government can't host the government's websites using tech from the government's country, maybe it would be better to just forget about the whole cyberweb thing altogether? Just turn it off?
  • otteromkram 3y ago
    I'd argue that AWS is much better suited than self-hosting because it's such an important service. Downtime becomes negligible and global reach vastly increases with comparably little cost.
  • 0xbadcafebee 3y ago
    That sentence was a little confusing. You're not happy that the government is hiring experts to run an important service?
    • dtnewman 3y ago
      Yes. RDS is a very reasonable choice if you are a tech company, let alone a govt org. The alternative isn’t “let’s host this ourselves” it is “let’s host this with Oracle at a much higher cost”.
      • 15457345234 3y ago
        The alternative - at government scale - is absolutely 'let's host this ourselves' and that's what they should be doing, to ensure that institutional expertise remains. They should also own and operate their own datacentres which should be physically secure, not shared with commercial ventures and guarded by the armed forces, not civilian security.
        • 0xbadcafebee 3y ago
          Why doesn't the government manufacture their own cars? They're going to lose institutional expertise in building cars! They should also own and operate their own manufacturing facilities which should be physically secure, not shared with some 'civilian commercial venture'. By golly, the government can't do business if it isn't a datacenter operations company, a software vendor, and a car manufacturer.
          • 15457345234 3y ago
            > By golly, the government can't do business if it isn't a datacenter operations company, a software vendor, and a car manufacturer. I mean, precisely, which is why some countries are rapidly turning into failed states. Too much buck-passing and outsourcing.
      • tobias_irmer 3y ago
        It isn't? AWS is crazy expensive and you don't have as much control over things as you may occasionally need. The best decision we took in the past few years with regards to infrastructure was moving away from AWS and doing everything ourselves. On RDS we had inexplicable spikes in cost, deteriorating support and no real support for any of our issues. When we tried using DMS, it just didn't work as expected, even after spending two days on the phone with their support.
  • pixelesque 3y ago
    As other comments point out, their own platform was (at least in terms of DB) already running on AWS, just using a different account.
    • foofie 3y ago
      > As other comments point out, their own platform was (at least in terms of DB) already running on AWS, just using a different account. That changes nothing. It just means this unjustifiable nonsense is going on for a while.
  • pmcp 3y ago
    As somebody who worked for the European Commission, and a european national government, I agree with your sentiment, but the harsh reality is that government divisions in generally work on a shoe string budget, when it comes to decisions like these. I wouldn’t be surprised if this was a “best effort given the circumstances” move.
  • _joel 3y ago
    There's an absolute ton of stuff on AWS. There used to be gCloud that allowed for smaller clouds to tender for government contracts bit there was a big pull to AWS, at least from my experience with it.
  • ivix 3y ago
    I'm surprised that you're surprised. Why on earth would government not be migrating to the cloud?
  • NomDePlum 3y ago
    Why? I've worked on a number of UK government projects, including some with particularly sensitive security and data requirements. Having some knowledge of their on-prem data centres and UK Cloud offering they have also used moving to AWS has so many operational, security and resilience benefits that aren't available elsewhere. It's not a free-lunch by any means and needs thought and governance certainly but the procurement simplification benefits alone make going to the public cloud a no brainer for a lot of government services. It is worth knowing that even the on-prem data centres are usually operated by 3rd parties such as HP, BT and IBM. There was an initiative to have "Crown-managed" data-centers but it's not particularly scalable.
  • overstay8930 3y ago
    If you saw how non-tech companies run datacenters, well let's just say they're not exactly working with NATO like the big 3 cloud providers do when designing their DCs and backbone. Honestly you should be frightened when you see someone NOT using a cloud provider, because it is hard work to properly run and secure a datacenter. Even Equinix fucks up HARD regularly and they are considered the gold standard (shout out to those I saw at 350 E Cermak over the weekend).
  • msla 3y ago
    It incentivizes public-private cooperation: If the government cracks down on Amazon, Amazon turns off the government's AWS accounts and deletes the data. The government finds that subpoenaing a wiped hard drive is utterly nugatory, and thereby learns humility.
  • mobilemidget 3y ago
    "The PaaS team offered us the ability to migrate databases using AWS Database Migration Service (DMS)." And I'm not surprised if, they got some kickback, discount etc in some way to promote AWS on their blog. Not claiming its so, but I would not be surprised at all. It reads as one big advertisement.
• mbb70 3y ago
  Interesting to compare this to https://knock.app/blog/zero-downtime-postgres-upgrades https://knock.app/blog/zero-downtime-postgres-upgrades discussed here https://news.ycombinator.com/item?id=38616181 https://news.ycombinator.com/item?id=38616181 A lot of the discussion boiled down to 'this is a lot of complexity to avoid a few minutes of downtime'. I guess this is the proof, just use AWS Data Migration Service, swap the DNS entries to go live and live with 11 seconds of downtime.
  • ris 3y ago
    There is no "just" about it. The absolute key takeaway is in "what we learned": > We chose to use DMS because it was well supported by the GOV.UK PaaS and we could also get support from AWS. If we were doing a PostgreSQL to PostgreSQL database migration in the future, we would invest more time in trying alternative tools such as pglogical. DMS potentially added more complexity, and an unfamiliar replication process than what we may have found with other tools. This backs up what AWS say themselves on PostgreSQL to PostgreSQL migrations. The message here is not "just use DMS".
    • T-Winsnes 3y ago
      Even AWS in their own docs says to use the native tools when migrating from postgres to postgres[1]. They don't go into the details to much and points to pg_dump rather than pg_logical, but interesting to see that they don't recommend using DMS for it [1] https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.PostgreSQL.html#CHAP_Source.PostgreSQL.Homogeneous https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source...
      • ris 3y ago
        They do, but those recommendations are buried quite deep in the documentation, well behind all the marketing guff that suggests that DMS is all things to all people, and wonderful magic that is ideal for all situations.
  • btown 3y ago
    Has anyone used https://cloud.google.com/database-migration/docs/postgres/quickstart https://cloud.google.com/database-migration/docs/postgres/qu... to do something like this? Does it work similarly to AWS DMS?
• deleted 3y ago
  [deleted]
• _xnmw 3y ago
  Now all we need is for Amazon to come out with a "government-as-a-service" product for your budding nation state.
  • ris 3y ago
    FWIW GOV.UK Notify is part of a suite of services offered by GDS to UK public sector bodies (along with GOV.UK Pay and GOV.UK PaaS) that was originally known as "Government As A Platform".
    • robin_reala 3y ago
      …and the platform is all open source, so people are free to fork / steal. https://github.com/orgs/alphagov/repositories?q=paas https://github.com/orgs/alphagov/repositories?q=paas
  • hinkley 3y ago
    In partnership with pinkerton.com
• londons_explore 3y ago
  There are various ways to 'pause' incoming postgres queries, for example using pgbouncer, - ie. don't fail them, simply delay them until the replication has caught up and then let them continue on the new database. If anything goes wrong and replication doesn't catch up, you can unpause and let those queries happen on the old database. Therefore, your 11 seconds of downtime becomes 0 to 11 seconds of added page load time. But more importantly, of the thousands of users of the database who have never seen a query fail before and might have buggy error handling codepaths or have a single failed query ruin a whole batch job, this approach leads to a lot less collateral damage.
  • whartung 3y ago
    It’s one thing to pause queries but can you also pause transactions that are in flight? How does that work?
• londons_explore 3y ago
  Note that the enemy of low/zero downtime migrations like this is long running queries. Ie. a single update query which takes 30 mins. You either have to kill and roll back that query, or suffer 30 mins of unavailability. As far as I know, there is no way to migrate a currently in progress query.
  • Amezarak 3y ago
    It's hard for me personally to imagine a 30-minute update query that is not written extremely inefficiently, or else a one-time huge data migration. There are a lot of the former in the wild to be sure. I've had a lot of run turning minutes-hours into milliseconds. :)
    • londons_explore 3y ago
      Data scientists... And when you look at the query, it'll be 800 lines of SQL...
      • hobs 3y ago
        Heh, that's not so bad - 2 jobs ago I had to fix a KPI generation process that was 70k lines of dynamic sql, that unwrapped to up to 1m LOC :)
        • chaz6 3y ago
          Did you ever run into a hard limit of statement size?
          • hobs 3y ago
            No, but all the code generation was happening in the server itself so I dont know how hard and fast it applies, iirc SQL Server's limits are like 64k x packet size.
  • necovek 3y ago
    For a software engineering project, you probably want to limit your transactions to much less than that (set statement_timeout is your friend). If you've got extremely long transactions, you can probably avoid doing the switch-over when they run (hopefully they are not a random occurrence but a result of a scheduled job or similar). In combination with transaction time limit and fail-over configuration (where you fail the old primary), you can control the slowdown (instead of downtime, eg. with pgbouncer) very precisely. I would be more concerned with the DNS TTL being respected in the entire stack (and external caching DNS servers you rely on), tbh. But it is usually not critical to avoid a dozen seconds of downtime for an app, so whatever is simpler for you should be your go to solution.
• Topgamer7 3y ago
  We tried to work with DMS to migrate mysql to postgres, and it was a nightmare. Support was useless, and would often just not get back to us without prodding. Then them giving us canned responses unrelated to our queries. The whole thing is nigh on un-debuggable. Stay away.
  • rjh29 3y ago
    Tried it for mysql and it was flat out broken and silently corrupted data.
    • Topgamer7 3y ago
      For us it seemed to be trying to load data from the wrong table on mysql, into the wrong table on postgres.
  • mey 3y ago
    I worked on migrating our MySQL system to PostgreSQL using pgloader ( https://pgloader.io/ https://pgloader.io/ ). There were some hiccups, things that needed clarification in documentation, and some additional processes that needed to be done outside of the system to get everything we need in place, it was a amazing help. Not sure the project would've been possible without it. Data mapping from PostgreSQL to PostgreSQL as in the article isn't nearly as bad as going between systems. We took a full extended outage and didn't preload any data. There were many dry runs before hand and validation before hand, but the system wasn't so mission critical that we couldn't afford to shutoff the system for a couple of hours.
    • Topgamer7 3y ago
      We also ended up using pgloader. Its not without its friction either. For example the concurrency/number of rows setting seems broken out the gate, and its like playing darts with a blindfold on to get it to run without running out of memory. But being able to read the source, github actions, and overall at least I could debug my problems, or find others who had the same issue. Would recommend pgloader.
  • 3y ago
• karol 3y ago
  Hope the picture is illustrative only.
• aidos 3y ago
  I love that where the rubber meets the road it doesn’t matter if you’re a government organisation or a web agency, it’s still just plain old Postgres, python, sqlalchemy and dns with a low ttl.
  • NegativeK 3y ago
    To be fair, there's plenty of government orgs at the bottom and web agencies at the top.
• Ozzie_osman 3y ago
  We did a similar migration (somewhat larger database) with ~20 seconds of downtime and much less work... using the magic of AWS RDS Blue-Green Deployments [1]. Surprised they aren't mentioned in the thread yet. Basically, you spin up a new Blue Green deployment with any desired changes (in our case, we were upgrading Postgres major from 13 to 15). While your blue configuration continues to serve traffic, AWS uses logical replication to keep the "green" deployment in-sync. You can keep modifying (or testing) the "green" deployment (eg you could load test it if you wanted to), as long as you don't do any writes to it (writes still have to go to your live, blue configuration, and are replicated to green). When you're ready, you run the "switch" command, and AWS does a few things for you: run checks to ensure blue/green are in sync, stops writes and connections, waits a few seconds to ensure replication is caught up, renames your database, then allows connections/writes again. We had less than 20 seconds of downtime, by our count. And, we had a primary and several read replicas and AWS successfully switched the full configuration over with no hiccups. You don't even need to switch your configuration because AWS swaps the database URLs for you. Green becomes blue, blue becomes old blue, and when you're ready, you delete "old blue". Highly recommend! They do have some restrictions (for instance, not sure if it would work if you're switching accounts, etc). 1. https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/blue-green-deployments.html https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/blue-...
  • sgarland 3y ago
    +1 for B/G. That said, I imagine they couldn’t use it due to the cross-account shift. I’ve used it for both MySQL (with much higher QPS than TFA, by two orders of magnitude) and Postgres, and they both went flawlessly. Read the docs, especially the limitations. Re-read them. Do a test run in the dev environment, under load. Do it again in staging. Or just YOLO into prod ‘cause it’ll probably be fine, I guess.
    • Ozzie_osman 3y ago
      We definitely did a dry run with a parity configuration a couple nights before. It gave us a lot more confidence.
  • 3y ago
• ComputerGuru 3y ago
  > The second change was to create a DNS record in AWS Route53 for `database.notifications.service.gov.uk` with a 1 second TTL (time to live) [..] our migration script just needed to update the DNS weighting in AWS to 100% of results being sent to the target database location and wait 1 second for the TTL to expire. Then, when our apps next try to query our database they will be querying our target database. Wait. Their (or Python's default?) db orm blocks while it performs a DNS lookup for each and every query!? It doesn't cache resolved addresses for any length of time? No connections are pooled and reused?
  • necovek 3y ago
    It would probably be the OS' `getaddrinfo` or `gethostname` that does this: Python rarely reimplements system level calls, which means it relies on the system's configuration. If TTL of 1s was respected, they would be cached for 1s, but it's not uncommon for DNS query libraries and especially caching DNS servers to not fully respect TTL anyway: tbh, that might explain some of the downtime they've seen.
    • ComputerGuru 3y ago
      I didn't mean it was directly implementing the networking call to the dns server -- just that it wasn't directly caching the result. getaddrinfo(3) and getnameinfo(3) (guessing that's what you meant) don't implement caching, at least not explicitly in the spec and not normally in practice. On Windows, DNS results are cached by the OS but on Linux that would be distro-dependent behavior and usually requires setting up a local caching dns server (Ubuntu uses unbound out-of-the-box, iirc. Other choices include ncsd and dnsmasq). Even if they implemented caching at the syscall level, this still assumes no connection stays open for more than 1s or is reused except per query. It seems like a big assumption (at least I hope it is, because I certainly wouldn't want my app to initialize a new db connection, let alone perform a DNS lookup, for every query).
      • juggertao 3y ago
        They mentioned they had a script which terminated all connections to the old database then changed the password. But on the app side you typically don't cache DNS, that creates other problems like stale DNS.
• ClassicOrgin 3y ago
  Minor detail but did anyone else notice they are using eu-west-1? Kind of weird for the UK to be hosting there sites in another country (Ireland). I'm sure this isn't super sensitive data but still.
  • lozenge 3y ago
    The London AWS region was missing a lot of features for a long time. It's easier to just go with a big region.
    • justinclift 3y ago
      "Lets go with the easier approach" is a bit worrying when it means potentially breaking security assumptions / legal assurances. Though I guess it could be explained away by having something in the website's "Terms and Conditions for use". ;)
      • juggertao 3y ago
        It's a gov website. What are they going to do, sue themselves?
        • another2another 3y ago
          Have a public enquiry, with lots of tea.
  • esskay 3y ago
    They've been on AWS since before eu-west-2 was added, it's still not at the scale of eu-west-1. Capacity issues are still a thing (but getting much better), and only recently have they become pretty much feature parallel.
  • callalex 3y ago
    It made a lot more sense before…you know…the thing that made no sense.
  • 3y ago
• gbraad 3y ago
  They don't just sent the notifications but store them? Sounds like it might contain PPI as it records passport extension data, etc. Might be minimal, though over 1 billion rows (400GB) sounds massive trove to keep around.
  • M2Ys4U 3y ago
    I'd highly doubt their database contains payment protection insurance.
    • gbraad 3y ago
      Typo: PII, Personally Identifiable Information
• efxhoy 3y ago
  Lovely! We just migrated from postgres 14 to 16 for 3 postgres clusters (servers) on RDS containing about 2TB of data across 8 databases. We were down from 00:00 to 04:00. Steps we took: * enabled our fallback "maintenance mode" site. It's a super lightweight version of our site running on CF workers. * scaled down all apps using the db to 0 in terraform * hit the upgrade button in the aws web ui, which runs pg_upgrade. 14->15 * waited for it to finish * hit the upgrade button again. 15->16 * waited for the dbs to start accepting connections (they do before they're marked as ready, I think aws does more stuff than pg_upgrade) * Started `VACUUM ANALYZE; REINDEX DATABASE CONCURRENTLY`. The idea is to avoid performance issues between versions and make use of performance improvements from new versions. * Started spinning up the apps again * Waited until all apps had a handful of containers running * Started accepting traffic (disabled maintenance site) * Went to bed The REINDEX CONCURRENTLY happily chugged along for the biggest db for another 18 hours without blocking anything. Next time we're doing aws blue/green deploys to avoid downtime. We didn't this time since we weren't on 14.9 yet (the minimum minor version of 14 supported by blue green). If I was doing this myself I wouldn't pay the AWS tax, instead do blue/green myself with logical replication and a load balancer.
  • sharadov 3y ago
    I would just use pg_upgrade with --hardlinks for an in-place upgrade. Have done 2 TB dbs in less than a minute. We were running our own Postgres instances on-prem.
• vfclists 3y ago
  This doesn't seem to bode well for Oracle, but lobbying trumps the day.
• MarjorieNapper 3y ago
  [dead]
• saisrirampur 3y ago
  Very clear and concise blog! Loved reading it. I'd be very curious to see how Amazon DMS performs at scale. Scale includes either of these situations: a) Larger dataset - 2+TB b) Higher throughputs - WAL Spikes (at least 2-3K TPS) c) Reliably and efficiently replicating TOAST Columns (ex: large JSONBs). d) Advance data-types - BLOB, CLOB, HSTORE, ARRAYs etc. In my previous role with the Azure Postgres team, we observed that Azure DMS worked pretty seamlessly in migrations that did not involve the above situations. Once either of the above came in, the replication experience was hairy. Interestingly, in my current gig at PeerDB, many use-cases we are seeing have either of the above situations. We have been doing quite a surgical optimizations to handle those situations and they keep coming! That is the beauty of Postgres, enabling a myriad of workloads, each of the unique in their own way! :)
• oulu2006 3y ago
  We didn't even use red/green deployment; just had a multi-AZ deployment and migrated from 11.x -> 15.2 with about 30 seconds of downtime. No dramas really, didn't even need logical replication.
  • ris 3y ago
    I'll bet that wasn't across AWS accounts though.
• daguava 3y ago
  [dead]
• sharadov 3y ago
  DMS is a terrible migration tool, I spent almost a month fighting with various migration issues before I gave up. It would not migrate text and json types. Even AWS support could not offer a solution. We got in early testing AWS Blue/Green and that has made close to zero downtime upgrades a reality.
  • slyall 3y ago
    If you think DMS is a bad migration tool then try using it for ongoing replication to an external destination. Completely broken.
• deleted 3y ago
  [deleted]
• deleted 3y ago
  [deleted]
• ryandv 3y ago
  I've also used DMS to migrate smaller datasets (~200GB) from AWS RDS MySQL 5.7 to RDS PostgreSQL 11. 10 seconds of downtime here was actually incurred not due to the migration itself, but to enable MySQL binary logging on the RDS instance, which requires a restart, and which AWS DMS uses to replicate changes from the replication source (MySQL) to the target (PostgreSQL). Traffic was steered to the new PostgreSQL instance not with DNS/Route 53 weighted records, but an application-level percentage enroller (based on user ID). Our particular set-up did in fact have apps talking to both databases simultaneously, each with a percentage share of traffic, and so we did not need to incur additional downtime to cut off traffic to the original source database - though now you do have to worry about eventual consistency. I wouldn't recommend using their Schema Conversion Tool. We instead migrated the data as 1-to-1 as possible into the PostgreSQL target table, and then used plpgsql triggers on the replication target table to clean/validate the data and write it to another table with our desired (and more strongly typed - no more storing JSON as TEXT) schema. There were also some issues with the replication task seeming to stall and stop during the change data capture (CDC) phase. As mentioned support is kind of spotty in this area, though we learned it may have to do with sizing the DMS replication instance correctly.
• zImPatrick 3y ago
  I really love how verbose and up to date the UK with tech
• DeathArrow 3y ago
  Seems bad that government services depend on clod providers.
  • callalex 3y ago
    Why? Do you deny the benefits of shared hosting in its entirety?
    • DeathArrow 3y ago
      No. But I wish government agencies depend less on other entities. A government agency isn't in a business to make money. They should be concerned less with economic efficacy and more with accomplishing their goals. They have a fiduciary duty towards the citizens.
      • mattsan 3y ago
        Out of all the entities to depend on, AWS is tried and battle tested with US gov. Additionally, a pandemic has shown that government services actually need to scale to arbitrary amounts, seemingly at random. Don't you think that in this case using AWS is better to simply guarantee availability? Imagine tax payers money being spent on servers and then a pandemic happens and when the economy is screeching to a halt, more tax payers money is needed to expand the cluster, money that really would be useful to spend elsewhere.
      • patmorgan23 3y ago
        And what if AWS is an efficient, efficiency, and affordable way to achieve that goal?
      • eightnoteight 3y ago
        > A government agency isn't in a business to make money. true, but it's not in the business of wasting money either. if they don't take care about economic efficacy, then someday voters are going to judge them for wasting tax payers money
• denysvitali 3y ago
  They could have probably used pgpool [1] to avoid relying on the DNS (you never know in the chain who's not respecting the TTL). With this, you can choose which queries are ending up where - and migrating the DB endpoint can be done once, centrally [1]: https://www.pgpool.net/docs/latest/en/html/ https://www.pgpool.net/docs/latest/en/html/
• speculator 3y ago
  nice writeup. easy to read, easy to understand
• pedrokost 3y ago
  We recently completed the migration of a self-hosted 3 TB PostgreSQL database from version 12 to 16, transitioning from Ubuntu 18 to Ubuntu 22. Concurrently, we had to upgrade various extensions, most notably Timescale, for which a compatible version did not exist across all scenarios. We performed the upgrade by updating a replica in the following sequence: - Start: PG12, Ubuntu 18, TS2.9 - Step 1: Set up a read-only replica with PG12 on Ubuntu 22, maintaining TS2.9. - Step 1.5: Enter maintenance mode and halt all services. - Step 2: Detach the the read-only replica, upgrading from PG12 to PG15 on Ubuntu 22 with TS2.9. - Step 3: Upgrade from PG15 with TS2.9 to TS2.13 on Ubuntu 22. - Step 4: Upgrade from PG15 to PG16 on Ubuntu 22 with TS2.13. - Step 4.5 : Reconnect services to the new database server, resume all services, and exit maintenance mode. All the database upgrade steps were well-tested and automated using Ansible. Nonetheless, we did encounter an issue that had not arisen during testing. This extended our downtime to approximately half an hour, which, for our use case, was perfectly acceptable. Employing logical replication could have mitigated the last-minute surprise. So we will consider this approach for our next upgrade cycle.
  • pbrooko 3y ago
    We recently followed an almost identical upgrade path (however at the time PG16 wasn't yet supported by Timescale, so stopped at PG15 + TS 2.12). We did look into using logical replication to reduce the downtime of the upgrade, but because database schema and DDL commands aren't replicated, it seems that it isn't recommended with Timescale in the loop.. (I suppose the underlying schema changes that Timescale needs to make under the hood are mostly a function of your hypertable chunk sizing and what your incoming writes look like, so this could be planned around / timed well, but we felt it added too much potential complexity & risk compared to simply opting for a small maintenance window while pg_upgrade completed).
• globular-toast 3y ago
  Is that a picture of them doing it? What is this weird fantasy that programming looks like this? It's always the same: a couple of people, always of diverse backgrounds, physically interacting, usually pointing and laughing at something, with perhaps another group, representing different demographics, looking on with a mixture of curiosity and awe. Do an image search for programming to see more examples of this. I guarantee this work was the result of guys sitting at desks, possibly in the dark, thinking. Are we collectively embarrassed that this is what programming looks like? Or are these just fantasies of management types who have never written a line in their lives?
  • johneth 3y ago
    Give it a rest, mate.
    • globular-toast 3y ago
      Nah, this is the thing that leads to open offices etc. I want people to understand what programming actually looks like and these silly pictures need to go.
  • draaglom 3y ago
    The primary goal of most large organisations' dev blog is to attract potential candidates to the top of the recruitment funnel. This picture appears to be (presumably) the actual team doing a team building activity. This is both a reasonable choice given the inferred instrumental goals of the blog, and a honest reflection of (one part of) the team life, assuming it's a photo of the real team.
  • beejiu 3y ago
    They are clearly not programming. It's a team building game called the marshmallow challenge.
• alerter 3y ago
  Interesting, though I have no idea why the government is using AWS in the first place. This isn't a startup hacking away trying to find PMF, or dealing with unpredictable marketing-driven traffic spikes. We know we need these services running long term, and can make solid predictions about usage patterns. We could build a public sector cloud and/or adopt a sensible on-prem approach. This requires funding, coordination and technical leadership, but would save the taxpayer an enormous amount over the long term. Public sector IT is a disaster in general ofc, but I know there are good engineers working there.
  • MrBuddyCasino 3y ago
    If you think the public sector could improve its operational efficiency by building, operating and using their own cloud, I've go a bridge to sell you.
  • rjzzleep 3y ago
    I don't know about the UK, but AWS has has GovCloud in the US for a long time, and to be honest compared to a lot of infrastructure I have seen there it's a blessing. On the flipside, I've met some really amazing infrastructure and ops people in a German gov healthcare institution running the in-house DC, where the problem was neither the tech, nor the people, but 100% the management and their processes, and their desire to be the bottleneck for every single interaction between infrastructure and engineering teams.
  • StupidOne 3y ago
    I'm sure a lot of countries in EU did this. First hand I know, they did this in Croatia as I was one of the developer who had to use it to deploy on it. The worst thing I have ever seen in my life. And I worked on a lot legacy apps written in VB.NET, Web forms, old Sharepoint, Basic and even when the whole app was one big mess of store procedures. AWS, Azure, GC are at least written with thought about end users (us, developers) while government cloud was architectured, designed and built by the lowest bidder whose first goal was to cut and cut and cut his costs whenever possible.
  • jamietanna 3y ago
    The UK government as a whole operates across the big names in the public cloud as well as some on-Prem/colo. I'd very much recommend watching https://youtube.com/watch?v=mpY1lxkikqM&pp=ygUOUmljaGFyZCB0b3dlcnM%3D https://youtube.com/watch?v=mpY1lxkikqM&pp=ygUOUmljaGFyZCB0b... from September about Gov.UK's various iterations and some of the migrations across cloud that they've had to do. One thing about (at least UK government) is that procurement requirements means that they go to market for quotes around usage every few years. If ie Oracle Cloud was 1/10th the price, it would likely mean they'd win the deal, and so would have to migrate to Oracle for the duration of the contract, and then potentially do the same to another cloud if that was cheaper
• jm2dev 3y ago
  On a similar case AWS DMS did not work for my team and we proceeded with pglogical. Although it has some limitations it worked pretty well, and personally I like that it is cloud agnostic. Definitively I would recommend to consider pglogical first.
• rthkljlkrj 3y ago
  [dead]
• zeroclicks 3y ago
  Let's ignore the technicalities completely. Here's a government providing a detailed look into their engineering practices, complete with graphs and configuration snippets. How many governments manage to publish such a thing?
• glintik 3y ago
  11 seconds downtime - looks like devops had a break for smoking
• mwarkentin 3y ago
  Back when we first tried out DMS there was a fun bug where booleans were interpreted as strings, so all false records were interpreted as “false” and translated to true on the target DB. It was fixed shortly after but was a good reminder to validate your data during a migration.