CURL and WGET missing from current container

[dvasdekis]

Hey folks. It looks like both curl and wget are missing from the current container? Neither are in /bin , and additionally I get:

docker exec -it local_env_ib-gateway9_1 wget
OCI runtime exec failed: exec failed: container_linux.go:346: starting container process caused "exec: \"wget\": executable file not found in $PATH": unknown
docker exec -it local_env_ib-gateway9_1 curl
OCI runtime exec failed: exec failed: container_linux.go:346: starting container process caused "exec: \"curl\": executable file not found in $PATH": unknown

Any idea where they've gone? They're a prerequisite for the health checks described here.

[shahidhk]

@dvasdekis Health checks are typically done from outside the container. We do not package curl or wget in the interest of keeping the image size lean.

Can you give more hints on your use case?

[lexi-lambda]

My guess is that @dvasdekis is interested in using the Docker built-in HEALTHCHECK feature, which unfortunately only supports running commands inside the container.

That said, I’m not actually that familiar with HEALTHCHECK, since in all deployments of Docker I’ve used, the load balancer had some external mechanism for checking health, as you allude to. I don’t know what systems actually consume the built-in HEALTHCHECK information (maybe Docker Swarm…?), so I’d also like to know more details about the use case.

[dvasdekis]

Correct @lexi-lambda - I'm personally using Docker-Compose, and in order to bring the containers up in the right order and ensure that they're available, the container has to be able to run a command that reports its health. In my case, I want this healthcheck to only be successful after the migrations have finished running. A command might be curl -H "content-type: application/json" -X POST --data 'query { tbl_myschema_version { version_id } }' http://localhost:8080/v1/graphql || exit 1, where tbl_myschema_version is written to as the last step in the migrations process.

[shahidhk]

Looks like docker-compose recommends running a command inside the container to do health checks [ref].

@dvasdekis I just checked the latest image and wget seems to be present at /bin/wget.

What version are you on?

[dvasdekis]

I see it too now. I must have been on an old version. I'm so sorry, not sure why it didn't appear when I looked in the container I was running!
Thank you!!

[dvasdekis]

For those looking to use wget to perform GraphQL requests, the syntax is:
wget --header 'content-type: application/json' --post-data='{ "query": "{ tbl_hedgecheap_version { version_id } }" }' -q -O - http://localhost:8080/v1/graphql.

[Toub]

For those interested, you can also use hasura /healthz api as docker healthcheck:

    healthcheck:
      test:  wget --no-verbose --tries=1 --spider http://0.0.0.0:8080/healthz || exit 1
      interval: 5s
      timeout: 5s
      retries: 5

Related links:

• https://hasura.io/docs/1.0/graphql/core/api-reference/health.html
• https://stackoverflow.com/a/47722899/1097926

[davidpanic]

curl and wget also seem to be missing in v2.0.0-alpha.2

Is there another way of doing health checks in docker compose? Relying on containers having curl available seems kind of dumb...

[davidpanic]

If anyone is still wanting to do hasura healthchecks with docker-compose, I've found an alternate solution using bash and commands that are available pretty much anywhere:

healthcheck:
  test: ["CMD", "bash", "-c", "exec 5<>/dev/tcp/127.0.0.1/8080 && echo -e 'GET /healthz HTTP/1.1\n\n' >&5 && cat <&5 | head -n 1 | grep 200"]
  interval: 5s
  timeout: 5s
  retries: 3

[m-rgba]

Slightly more intensive, but I've seen this done as well.
Pretty much adding curl during the first healthcheck without having to use a custom dockerfile. Going to have a slight amount of overhead on each check though.

healthcheck:
  test: ["CMD-SHELL", "apt-get update -y && apt-get install -y curl && curl --fail http://localhost:8080/healthz || exit 1"]
  interval: 5s
  timeout: 3s
  retries: 5

[ajayvignesh01]

Slightly more intensive, but I've seen this done as well. Pretty much adding curl during the first healthcheck without having to use a custom dockerfile. Going to have a slight amount of overhead on each check though.

healthcheck:
  test: ["CMD-SHELL", "apt-get update -y && apt-get install -y curl && curl --fail http://localhost:8080/healthz || exit 1"]
  interval: 5s
  timeout: 3s
  retries: 5

Or instead of doing that every time, you could just add installing curl to your Dockerfile to only install during build
RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/*