Docker Container Logging using Promtail

promtail_docker_logs.md

Inspired By: grafana/loki#333

• docker-compose.yml

version: "3"

networks:
  loki:

services:
  loki:
    image: grafana/loki:1.4.1
    ports:
      - "3100:3100"
    command: -config.file=/etc/loki/local-config.yaml
    networks:
      - loki

  promtail:
    image: grafana/promtail:1.4.1
    volumes:
      - /var/lib/docker/containers:/var/lib/docker/containers
      - /home/ubuntu/docker-config.yml:/etc/promtail/docker-config.yml
    command: -config.file=/etc/promtail/docker-config.yml
    networks:
      - loki

  grafana:
    image: grafana/grafana:master
    ports:
      - "3000:3000"
    networks:
      - loki

• docker-config.yml

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:

- job_name: system
  static_configs:
  - targets:
      - localhost
    labels:
      job: varlogs
      __path__: /var/log/*log

- job_name: containers
  entry_parser: raw

  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      __path__: /var/lib/docker/containers/*/*log

  # --log-opt tag="{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"
  pipeline_stages:

  - json:
      expressions:
        stream: stream
        attrs: attrs
        tag: attrs.tag

  - regex:
      expression: (?P<image_name>(?:[^|]*[^|])).(?P<container_name>(?:[^|]*[^|])).(?P<image_id>(?:[^|]*[^|])).(?P<container_id>(?:[^|]*[^|]))
      source: "tag"

  - labels:
      tag:
      stream:
      image_name:
      container_name:
      image_id:
      container_id:

$ docker-compose up -d

$ docker run -itd --name nginxapp  -p 8080:80 --log-driver json-file --log-opt tag="{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}" nginx
$ curl http://localhost:8080/?foo=bar

Screenshot:

Setup with less labels:

• docker-config.yml

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:
- job_name: containers
  entry_parser: raw

  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      cluster: multipass-cluster
      __path__: /var/lib/docker/containers/*/*log

  # --log-opt tag="{{.Name}}"
  pipeline_stages:

  - json:
      expressions:
        stream: stream
        attrs: attrs
        tag: attrs.tag

  - regex:
      expression: (?P<container_name>(?:[^|]*[^|]))
      source: "tag"

  - labels:
      #tag:
      stream:
      container_name:

$ docker run -itd --name nginxapp3  -p 8080:80 --log-driver json-file --log-opt tag="{{.Name}}" nginx
$ curl -XGET -A "Mozilla" --refer http://bot.com/scrape.html http://localhost:8080/?foo=barx

Screenshot:

Make sure to pass either to docker command

--log-driver json-file --log-opt tag="{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"

--log-driver json-file --log-opt tag="{{.Name}}"

As seen in first post

Files aren't copied in /var/lib/docker/containers. Do we need sudo privileges for it?

yes, on linux you need to have elevated rights to access it.
If using Windows (WSL2) you are totally out of luck anyways, there its not accessible easily at all.

Hi everyone,

In the official doc : https://docs.docker.com/config/containers/logging/json-file/ , "tag" isn't on the drivers opts list.

So, as mentionned upper, for docker run cli use :
--log-opt tag="{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"

For docker compose :

    logging:
      driver: "json-file"
      options: 
        tag: "{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"

And for directly add this to the /etc/docker/daemon.json :

{
   "experimental":true, 
   "metrics-addr":"0.0.0.0:9323", 
   "insecure-registries":[
      "vip-registry-cache.domain.tld:5000", 
      "vip-registry-build.domain.tld:5001" 
   ],
   "hosts":[
      "tcp://0.0.0.0:2375", 
      "unix:///var/run/docker.sock" 
   ], 
   "log-driver": "json-file",
   "log-opts": {
      "tag": "{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"
   }
}

Files aren't copied in /var/lib/docker/containers. Do we need sudo privileges for it?

This worked for me for Docker Mac & Linux...

volumes:
  - /var/lib/docker/:/var/lib/docker:ro    

How can I cut the name into multiple and assign them to different tags, such as my container_name="k8s_httpbin_httpbin-2_lgy_ae8b8ca4-586e-4f60-b3b0-e80e1a4d0e72_0", but I want to convert this name into
pod="httpbin- 2"
namespace="lgy" this format

Since only root has access to /var/lib/docker and I'm running the Grafana agent under its own user on the host itself, changing the permissions to that directory seemed like a bad idea to me. After a bit of research I figured out how to make this work using the journald driver, which works nicely.

Docker Compose:

x-logging:
  &default-logging
  driver: "journald"
  options: 
    tag: "{{.Name}}"

services:
  # for each service you want to log
  some-service:
    # ...
    logging: *default-logging

Promtail (or Grafana agent) config:

      scrape_configs:
        - job_name: journal
          journal:
            labels:
              job: journal
          relabel_configs:
            # services
            - source_labels:
                - __journal__systemd_unit
              target_label: unit
            # docker containers
            - source_labels:
                - __journal_container_name
              target_label: container  # use whatever label you like

Hint: Promtail adds a __journal_ prefix to all fields - use something like this to see what's available:

journalctl -o json-pretty -u docker -n 10

Hi.
Thanks for your code. I appreciate it !

The question is about multiline stage. I configured promtail with less labels. But loki does not shows all the logs, shows only the last row.

• For example the actual log is:

warn: Ocelot.Responder.Middleware.ResponderMiddleware[0]
      requestId: GM:02, previousRequestId: no previous request id, message: Error Code: ConnectionToDownstreamServiceError Message: Error connecting to downstream service, exception: System.Net.Http.HttpRequestException: Connection refused (microservice:port)
       ---> System.Net.Sockets.SocketException (111): Connection refused
         at System.Net.Http.ConnectHelper.ConnectAsync(Func`3 callback, DnsEndPoint endPoint, HttpRequestMessage requestMessage, CancellationToken cancellationToken)
         --- End of inner exception stack trace ---
         at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
         at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
         at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
         at Ocelot.Requester.HttpClientHttpRequester.GetResponse(HttpContext httpContext) errors found in ResponderMiddleware. Setting error response for request path:/api/ping, request method: GET

• Shows only:

 at Ocelot.Requester.HttpClientHttpRequester.GetResponse(HttpContext httpContext) errors found in ResponderMiddleware. Setting error response for request path:/api/ping, request method: GET

Could you help me about that?

There is an approach the leaves the tag and the unnecessary any per-service logging: options: settings.

It requires an extra entry in daemon.json however - the addition of a log-opts:labels, or log-opts:labels-regex to allow the com.docker.* labels that docker attaches to containers when doing stack, service or compose deployments.

  "log-driver": "json-file",
  "log-opts": {
    "labels-regex": "^.+",
  }

Once this is done, one can verify the new labels being added to logs using --details

docker logs <container_id> --details

Now that these labels are present in the logs, promtails config can be:

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:

- job_name: containers
  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      __path__: /var/lib/docker/containers/*/*log

  pipeline_stages:
  - json:
      expressions:
        log: log
        stream: stream
        time: time
        tag: attrs.tag
        compose_project: attrs."com.docker.compose.project"
        compose_service: attrs."com.docker.compose.service"
        stack_name: attrs."com.docker.stack.namespace"
        swarm_service_name: attrs."com.docker.swarm.service.name"
        swarm_task_name: attrs."com.docker.swarm.task.name"
  - regex:
      expression: "^/var/lib/docker/containers/(?P<container_id>.{12}).+/.+-json.log$"
      source: filename
  - timestamp:
      format: RFC3339Nano
      source: time
  - labels:
      stream:
      container_id:
      tag:
      compose_project:
      compose_service:
      stack_name:
      swarm_service_name:
      swarm_task_name:
  - output:
      source: log

This

• sets the container_id from the path
• sets the timestamp correctly
• passes "tag" through so that it can be used for extra stack defined filtering
• generates "compose_project", "compose_name" labels for docker compose deployed containers
• generates "swarm_service_name", "swarm_task_name" for swarm services
• generates "stack_name" for containers deployed from a stack.

Thank you.
I'll try it and let you know the result

@chrisbecke this works great.

Thanks!

There is an approach the leaves the tag and the unnecessary any per-service logging: options: settings.

It requires an extra entry in daemon.json however - the addition of a log-opts:labels, or log-opts:labels-regex to allow the com.docker.* labels that docker attaches to containers when doing stack, service or compose deployments.

  "log-driver": "json-file",
  "log-opts": {
    "labels-regex": "^.+",
  }

Once this is done, one can verify the new labels being added to logs using --details

docker logs <container_id> --details

Now that these labels are present in the logs, promtails config can be:

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:

- job_name: containers
  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      __path__: /var/lib/docker/containers/*/*log

  pipeline_stages:
  - json:
      expressions:
        log: log
        stream: stream
        time: time
        tag: attrs.tag
        compose_project: attrs."com.docker.compose.project"
        compose_service: attrs."com.docker.compose.service"
        stack_name: attrs."com.docker.stack.namespace"
        swarm_service_name: attrs."com.docker.swarm.service.name"
        swarm_task_name: attrs."com.docker.swarm.task.name"
  - regex:
      expression: "^/var/lib/docker/containers/(?P<container_id>.{12}).+/.+-json.log$"
      source: filename
  - timestamp:
      format: RFC3339Nano
      source: time
  - labels:
      stream:
      container_id:
      tag:
      compose_project:
      compose_service:
      stack_name:
      swarm_service_name:
      swarm_task_name:
  - output:
      source: log

This

• sets the container_id from the path
• sets the timestamp correctly
• passes "tag" through so that it can be used for extra stack defined filtering
• generates "compose_project", "compose_name" labels for docker compose deployed containers
• generates "swarm_service_name", "swarm_task_name" for swarm services
• generates "stack_name" for containers deployed from a stack.

Hi!
I tried but it doesn't work for me.

I solved it by multiline

There is an approach the leaves the tag and the unnecessary any per-service logging: options: settings.

It requires an extra entry in daemon.json however - the addition of a log-opts:labels, or log-opts:labels-regex to allow the com.docker.* labels that docker attaches to containers when doing stack, service or compose deployments.

  "log-driver": "json-file",
  "log-opts": {
    "labels-regex": "^.+",
  }

Once this is done, one can verify the new labels being added to logs using --details

docker logs <container_id> --details

Now that these labels are present in the logs, promtails config can be:

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:

- job_name: containers
  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      __path__: /var/lib/docker/containers/*/*log

  pipeline_stages:
  - json:
      expressions:
        log: log
        stream: stream
        time: time
        tag: attrs.tag
        compose_project: attrs."com.docker.compose.project"
        compose_service: attrs."com.docker.compose.service"
        stack_name: attrs."com.docker.stack.namespace"
        swarm_service_name: attrs."com.docker.swarm.service.name"
        swarm_task_name: attrs."com.docker.swarm.task.name"
  - regex:
      expression: "^/var/lib/docker/containers/(?P<container_id>.{12}).+/.+-json.log$"
      source: filename
  - timestamp:
      format: RFC3339Nano
      source: time
  - labels:
      stream:
      container_id:
      tag:
      compose_project:
      compose_service:
      stack_name:
      swarm_service_name:
      swarm_task_name:
  - output:
      source: log

This

* sets the container_id from the path

* sets the timestamp  correctly

* passes "tag" through so that it can be used for extra stack defined filtering

* generates "compose_project", "compose_name" labels for docker compose deployed containers

* generates "swarm_service_name", "swarm_task_name" for swarm services

* generates "stack_name" for containers deployed from a stack.

Thanks for your post! Freakin' awesome - great to use promtail and avoid the loki plugin. I had some minor tweaks for my setup but everything works like a dream. Hats off for ya!

Only thing I'll call out - you need a Docker CE version new than early 2021. They added the labels-regex option to the JSON logs about that time.

There is an approach the leaves the tag and the unnecessary any per-service logging: options: settings.

It requires an extra entry in daemon.json however - the addition of a log-opts:labels, or log-opts:labels-regex to allow the com.docker.* labels that docker attaches to containers when doing stack, service or compose deployments.

  "log-driver": "json-file",
  "log-opts": {
    "labels-regex": "^.+",
  }

Once this is done, one can verify the new labels being added to logs using --details

docker logs <container_id> --details

Now that these labels are present in the logs, promtails config can be:

server:
  http_listen_address: 0.0.0.0
  http_listen_port: 9080

positions:
  filename: /tmp/positions.yaml

clients:
  - url: http://loki:3100/loki/api/v1/push

scrape_configs:

- job_name: containers
  static_configs:
  - targets:
      - localhost
    labels:
      job: containerlogs
      __path__: /var/lib/docker/containers/*/*log

  pipeline_stages:
  - json:
      expressions:
        log: log
        stream: stream
        time: time
        tag: attrs.tag
        compose_project: attrs."com.docker.compose.project"
        compose_service: attrs."com.docker.compose.service"
        stack_name: attrs."com.docker.stack.namespace"
        swarm_service_name: attrs."com.docker.swarm.service.name"
        swarm_task_name: attrs."com.docker.swarm.task.name"
  - regex:
      expression: "^/var/lib/docker/containers/(?P<container_id>.{12}).+/.+-json.log$"
      source: filename
  - timestamp:
      format: RFC3339Nano
      source: time
  - labels:
      stream:
      container_id:
      tag:
      compose_project:
      compose_service:
      stack_name:
      swarm_service_name:
      swarm_task_name:
  - output:
      source: log

This

• sets the container_id from the path
• sets the timestamp correctly
• passes "tag" through so that it can be used for extra stack defined filtering
• generates "compose_project", "compose_name" labels for docker compose deployed containers
• generates "swarm_service_name", "swarm_task_name" for swarm services
• generates "stack_name" for containers deployed from a stack.

working, ty!

entry_parser: raw
it does not work

@chrisbecke you can remove entry_parser: raw if you want to use new versions of promtail
@Pl8tinium thank you very much, best solution for me!!!

@Pl8tinium dude you saved my life, no joke! thanks. I was dealing with the docker plugin but it locked all my containers, thanks to promtail and your answer i could implement the solution.

The docker plugin has a hard dependency to a loki instance. So if the Loki instance is down, you aren't able to start your containers, which is an absolute nogo. I would rather miss the log messages than miss my running containers...