Currently the docker driver does not remove tasks from its state map
when destroying the task, which leads to issues when restarting tasks in
place, and leaks expired handles over time.
We already have two other Kill tests (e.g.
TestDockerDriver_Start_Kill_Wait and
TestDockerDriver_Start_KillTimeout), so don't need yet another flaky
test.
Noticed an issue in Docker daemon failing to handle the OOM test case
failure in build https://travis-ci.org/hashicorp/nomad/jobs/468027848 ,
and I suspect it's related to the process dying so quickly, and
potentially the way we are starting the task, so added a start up delay
and made it more consistent with other tests that don't seem as flaky.
The following is the log line showing Docker returning 500 error condition; while we can probably handle it gracefully without retrying, the retry is very cheap in this case and it's more of an optimization that we can handle in follow up PR.
```
testlog.go:32: 2018-12-14T14:57:52.626Z [DEBUG] docker/driver.go:852: docker: setting container startup command: task_name=nc-demo command="/bin/nc -l 127.0.0.1 -p 0"
testlog.go:32: 2018-12-14T14:57:52.626Z [DEBUG] docker/driver.go:866: docker: setting container name: task_name=nc-demo container_name=724a3e77-8b15-e657-f6aa-84c2d3243b18
testlog.go:32: 2018-12-14T14:57:52.694Z [INFO ] docker/driver.go:196: docker: created container: container_id=362b6ea183f3c4ce472d7d7571ca47023cea1df0f5eb920827921716f17718be
testlog.go:32: 2018-12-14T14:57:53.523Z [DEBUG] docker/driver.go:416: docker: failed to start container: container_id=362b6ea183f3c4ce472d7d7571ca47023cea1df0f5eb920827921716f17718be attempt=1 error="API error (500): {"message":"cannot start a stopped process: unknown"}
"
testlog.go:32: 2018-12-14T14:57:55.394Z [DEBUG] docker/driver.go:416: docker: failed to start container: container_id=362b6ea183f3c4ce472d7d7571ca47023cea1df0f5eb920827921716f17718be attempt=2 error="API error (500): {"message":"cannot start a stopped process: unknown"}
"
testlog.go:32: 2018-12-14T14:57:57.243Z [DEBUG] docker/driver.go:416: docker: failed to start container: container_id=362b6ea183f3c4ce472d7d7571ca47023cea1df0f5eb920827921716f17718be attempt=3 error="API error (500): {"message":"cannot start a stopped process: unknown"}
"
```
Using `:latest` tag is typically a cause of pain, as underlying image
changes behavior. Here, I'm switching to using a point release, and
re-updating the stored tarballs with it.
Sadly, when saving/loading images, the repo digeset is not supported:
https://github.com/moby/moby/issues/22011 ; but using point releases
should mitigate the problem.
The motivation here is that docker tests have some flakiness due to
accidental importing of `busybox:latest` which has `/bin/nc` that no
longer supports `-p 0`:
```
$ docker run -it --rm busybox /bin/nc -l 127.0.0.1 -p 0
Unable to find image 'busybox:latest' locally
latest: Pulling from library/busybox
Digest: sha256:2a03a6059f21e150ae84b0973863609494aad70f0a80eaeb64bddd8d92465812
Status: Downloaded newer image for busybox:latest
nc: bad local port '0'
```
Looks like older busybox versions (e.g. `busybox:1.24` do honor `-p 0`
as the test expect, but I would rather update busybox to fix.
Some tests have containers that die almost immediately, and may die
and cleaned up before `driver.WaitUntilStarted` runs.
The causes for container dying seems special for each test:
* TestDockerDriver_Cleanup: `hello-world` image just emits a message and exits immediately
* TestDockerDriver_ForcePull_RepoDigest: the busybox image in `TestDockerDriver_ForcePull_RepoDigest` test didn't support `-p 0` argument
* TestDockerDriver_Entrypoint: with the entrypoint being `/bin/sh -c`, the command needs to be the entire string; otherwise, it ignores the comments
this allows us to drop a cyclical import, but is subobptimal as it
requires BaseDriver tests to move. This falls firmly into the realm of
being a hack. Alternatives welcome.
This removes a cyclical dependency when importing client/structs from
dependencies of the plugin_loader, specifically, drivers. Due to
client/config also depending on the plugin_loader.
It also better reflects the ownership of fingerprint structs, as they
are fairly internal to the fingerprint manager.
As part of deprecating legacy drivers, we're moving the env package to a
new drivers/shared tree, as it is used by the modern docker and rkt
driver packages, and is useful for 3rd party plugins.
This allows the container to be tagged with a user friendly image name
(e.g. `redis:3.2`) rather than the image ID (e.g.
`sha256:87856cc39862cec77541d68382e4867d7ccb29a85a17221446c857ddaebca916`).
Useful for human debugging, as well as some debugging and image scanning
tools.
This risks two bad changes:
1. Discrepancy in image resolution between docker and Nomad's image
loader.
* I checked the image creation paths in Nomad, and noticed that we
either pulled the image or inspect the image with the user provided
name.
2. A race in image tagging where the tag is modified between image
loading and container creation.
* I, personally, don't think this case is cause for concern, as it is
analogous to the task running a bit later. As long as the image is
still present, creating the container should be good.
