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Docker doesn't give you the proper tooling to not have to use e.g. apt-get in your Dockerfiles. For that reason, one might as well conflate them.

cpuguy83 3y ago
Docker doesn't give you the tooling to build a package and opts for you to bring the toolchain of your choice. Docker executes your toolchain, and does not prescribe one to you except for how it is executed. Nix is the toolchain, which of course has its advantages.
- clhodapp 3y ago
  In terms of builds and dependency management, Docker and nix actually work pretty similarly under the covers: Both are mostly running well-controlled shell commands and hashing their outputs, while tightly controlling what's visible to what processes in terms of the filesystem. The difference is that nix is just enough better at it that it's practical to rebase the whole ecosystem on top of it (what you refer to as a "toolchain") whereas Docker is slightly too limited to do this.
vergessenmir 3y ago
I'm not sure that this is a Docker problem but you do have a point. I've used docker from the very beginning and it always surprised me that users opted to use package managers over downloading the dependencies and then using ADD in the docker file. Using this approach you get something reproducible. Using apt-get in a docker file is an antipattern
- zmgsabst 3y ago
  Why? — I agree that it’s not reproducible, but so what? We have 2-3 service updates a day from a dozen engineers working asynchronously — and we allow non-critical packages to float their versions. I’d say that successfully applies a fix/security patch/etc far, far more often than it breaks things. Presumably we’re trying to minimize developer effort or maximize system reliability — and in my experience, having fresh packages does both. So what’s the harm, precisely?
  - clhodapp 3y ago
    This feels like moving the goalposts. This is on a thread which began with the statement that Docker is reproducible. Will we next be saying that, OK, it's an issue that Docker isn't reproducible, but it's doing it for a noble reason? Regardless.... I can give a few reasons that it matters, off the top of my head: 1) Debugging: It can make debugging more difficult because you can't trace your dependencies back to the source files they came from. To make it concrete, imagine debugging a stack trace but once you trace it into the code for your dependency, the line numbers don't seem to make any sense. 2) Compliance: It's extremely difficult to audit what version of what dependency was running in what environment at what time 3) Update Reliability: If you are depending on mutable Docker tags or floating dependency installation within your Dockerfile, you may be surprised to discover that it's extremely inconsistent when dependency updates actually get picked up, as it is on the whim of Docker caching. Using a system that always does proper pinning makes it more deterministic as to when updates will roll out. 4) Large Version Drift: If you only work on a given project infrequently, you may be surprised to find that the difference between the cached versions of your mutably-referenced dependencies and the actual latest has gotten MUCH bigger than you expected. And there may be no way to make any fixes (even critical bugfixes) while staying on known-working dependencies.

cpuguy83 3y ago

Docker doesn't give you the tooling to build a package and opts for you to bring the toolchain of your choice. Docker executes your toolchain, and does not prescribe one to you except for how it is executed. Nix is the toolchain, which of course has its advantages.

clhodapp 3y ago
In terms of builds and dependency management, Docker and nix actually work pretty similarly under the covers: Both are mostly running well-controlled shell commands and hashing their outputs, while tightly controlling what's visible to what processes in terms of the filesystem. The difference is that nix is just enough better at it that it's practical to rebase the whole ecosystem on top of it (what you refer to as a "toolchain") whereas Docker is slightly too limited to do this.

vergessenmir 3y ago

I'm not sure that this is a Docker problem but you do have a point. I've used docker from the very beginning and it always surprised me that users opted to use package managers over downloading the dependencies and then using ADD in the docker file. Using this approach you get something reproducible. Using apt-get in a docker file is an antipattern

zmgsabst 3y ago
Why? — I agree that it’s not reproducible, but so what? We have 2-3 service updates a day from a dozen engineers working asynchronously — and we allow non-critical packages to float their versions. I’d say that successfully applies a fix/security patch/etc far, far more often than it breaks things. Presumably we’re trying to minimize developer effort or maximize system reliability — and in my experience, having fresh packages does both. So what’s the harm, precisely?
- clhodapp 3y ago
  This feels like moving the goalposts. This is on a thread which began with the statement that Docker is reproducible. Will we next be saying that, OK, it's an issue that Docker isn't reproducible, but it's doing it for a noble reason? Regardless.... I can give a few reasons that it matters, off the top of my head: 1) Debugging: It can make debugging more difficult because you can't trace your dependencies back to the source files they came from. To make it concrete, imagine debugging a stack trace but once you trace it into the code for your dependency, the line numbers don't seem to make any sense. 2) Compliance: It's extremely difficult to audit what version of what dependency was running in what environment at what time 3) Update Reliability: If you are depending on mutable Docker tags or floating dependency installation within your Dockerfile, you may be surprised to discover that it's extremely inconsistent when dependency updates actually get picked up, as it is on the whim of Docker caching. Using a system that always does proper pinning makes it more deterministic as to when updates will roll out. 4) Large Version Drift: If you only work on a given project infrequently, you may be surprised to find that the difference between the cached versions of your mutably-referenced dependencies and the actual latest has gotten MUCH bigger than you expected. And there may be no way to make any fixes (even critical bugfixes) while staying on known-working dependencies.