Dozzle - dozzle.dev

Dozzle is a small lightweight application with a web based interface to monitor Docker logs. It doesn’t store any log files. It is for live monitoring of your container logs only.

dozzle-dark.mp4

Features

• Intelligent fuzzy search for container names 🤖
• Search logs using regex 🔦
• Small memory footprint 🏎
• Split screen for viewing multiple logs
• Download logs easy
• Live stats with memory and CPU usage
• Authentication with username and password 🚨

Dozzle should work for most. It has been tested with hundreds of containers. However, it doesn't support offline searching. Products like Loggly, Papertrail or Kibana are more suited for full search capabilities.

Dozzle doesn't cost any money and aims to focus on real-time debugging.

Getting Dozzle

Dozzle is a very small Docker container (4 MB compressed). Pull the latest release from the index:

$ docker pull amir20/dozzle:latest

Using Dozzle

The simplest way to use dozzle is to run the docker container. Also, mount the Docker Unix socket with --volume to /var/run/docker.sock:

$ docker run --name dozzle -d --volume=/var/run/docker.sock:/var/run/docker.sock -p 8888:8080 amir20/dozzle:latest

Dozzle will be available at http://localhost:8888/. You can change -p 8888:8080 to any port. For example, if you want to view dozzle over port 4040 then you would do -p 4040:8080.

Connecting with Docker compose

version: "3"
services:
  dozzle:
    container_name: dozzle
    image: amir20/dozzle:latest
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    ports:
      - 9999:8080

Connecting to remote hosts

Dozzle supports connecting to multiple remote hosts via tcp:// using TLS or without. Appropriate certs need to be mounted for Dozzle to be able to successfully connect. At this point, ssh:// is not supported because Dozzle docker image does not ship with any ssh clients.

To configure remote hosts, --remote-host or DOZZLE_REMOTE_HOST need to provided and the pem files need to be mounted to /cert directory. The /cert directory expects to have /certs/{ca,cert,key}.pem or /certs/{host}/{ca,cert,key}.pem in case of multiple hosts.

Below are examples of using --remote-host via CLI:

$ docker run -v /var/run/docker.sock:/var/run/docker.sock -v /path/to/certs:/certs -p 8080:8080 amir20/dozzle --remote-host tcp://167.99.1.1:2376

Multiple --remote-host flags can be used to specify multiple hosts.

Or to use compose:

version: "3"
services:
  dozzle:
    image: amir20/dozzle:latest
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /path/to/certs:/certs
    ports:
      - 8080:8080
    environment:
      DOZZLE_REMOTE_HOST: tcp://167.99.1.1:2376,tcp://167.99.1.2:2376

You need to make sure appropriate certs are provided in /certs/167.99.1.1/{ca,cert,key}.pem and /certs/167.99.1.2/{ca,cert,key}.pem for both hosts to work.

Adding health check

Dozzle doesn't enable healthcheck by default as it adds extra CPU usage. healthcheck can be enabled manually.

version: "3"
services:
  dozzle:
    container_name: dozzle
    image: amir20/dozzle:latest
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    ports:
      - 8080:8080
    environment:
      DOZZLE_LEVEL: trace
    healthcheck:
      test: [ "CMD", "/dozzle", "healthcheck" ]
      interval: 3s
      timeout: 30s
      retries: 5
      start_period: 30s

Security

You can control the device Dozzle binds to by passing --addr parameter. For example,

$ docker run --volume=/var/run/docker.sock:/var/run/docker.sock -p 8888:1224 amir20/dozzle:latest --addr localhost:1224

will bind to localhost on port 1224. You can then use a reverse proxy to control who can see dozzle.

If you wish to restrict the containers shown you can pass the --filter parameter. For example,

$ docker run --volume=/var/run/docker.sock:/var/run/docker.sock -p 8888:1224 amir20/dozzle:latest --filter name=foo

this would then only allow you to view containers with a name starting with "foo". You can use other filters like status as well, please check the official docker command line docs for available filters. Multiple --filter arguments can be provided.

Authentication

Dozzle supports a very simple authentication out of the box with just username and password. You should deploy using SSL to keep the credentials safe. See configuration to use --username and --password. You can also use docker secrets --usernamefile and --passwordfile.

Changing base URL

Dozzle by default mounts to "/". If you want to control the base path you can use the --base option. For example, if you want to mount at "/foobar", then you can override by using --base /foobar. See env variables below for using DOZZLE_BASE to change this.

$ docker run --volume=/var/run/docker.sock:/var/run/docker.sock -p 8080:8080 amir20/dozzle:latest --base /foobar

Dozzle will be available at http://localhost:8080/foobar/.

Analytics collected

Dozzle collects anonymous user configurations using Google Analytics. Why? Dozzle is an open source project with no funding. As a result, there is no time to do user studies of Dozzle. Analytics is collected to prioritize features and fixes based on how people use Dozzle. This data is completely public and can be viewed live using Data Studio dashboard.

If you do not want to be tracked at all, see the --no-analytics flag below.

Environment variables and configuration

Dozzle follows the 12-factor model. Configurations can use the CLI flags or environment variables. The table below outlines all supported options and their respective env vars.

Flag	Env Variable	Default
--addr	DOZZLE_ADDR	:8080
--base	DOZZLE_BASE	/
--hostname	DOZZLE_HOSTNAME	""
--level	DOZZLE_LEVEL	info
--filter	DOZZLE_FILTER	""
--username	DOZZLE_USERNAME	""
--password	DOZZLE_PASSWORD	""
--usernamefile	DOZZLE_USERNAME_FILE	""
--passwordfile	DOZZLE_PASSWORD_FILE	""
--no-analytics	DOZZLE_NO_ANALYTICS	false
--remote-host	DOZZLE_REMOTE_HOST

Troubleshooting and FAQs

I installed Dozzle, but logs are slow or they never load. Help!

Dozzle uses Server Sent Events (SSE) which connects to a server using a HTTP stream without closing the connection. If any proxy tries to buffer this connection, then Dozzle never receives the data and hangs forever waiting for the reverse proxy to flush the buffer. Since version 1.23.0, Dozzle sends the X-Accel-Buffering: no header which should stop reverse proxies buffering. However, some proxies may ignore this header. In those cases, you need to explicitly disable any buffering.

Below is an example with nginx and using proxy_pass to disable buffering.

    server {
        ...

        location / {
            proxy_pass                  http://<dozzle.container.ip.address>:8080;
        }

        location /api {
            proxy_pass                  http://<dozzle.container.ip.address>:8080;

            proxy_buffering             off;
            proxy_cache                 off;
        }
    }

What data does Dozzle collect?

Dozzle does collect some analytics. Analytics is anonymous usage tracking of the features which are used the most. See the section above on how to disable any analytic collection.

In the browser, Dozzle has a strict Content Security Policy which only allows the following policies:

• Allow connect to api.github.com to fetch most recent version.
• Only allow <script> and <style> files from self

Dozzle opens all links with rel="noopener".

We have tools that uses Dozzle when a new container is created. How can I get a direct link to a container by name?

Dozzle has a special route that can be used to search containers by name and then forward to that container. For example, if you have a container with name "foo.bar" and id abc123, you can send your users to /show?name=foo.bar which will be forwarded to /container/abc123.

I installed Dozzle but memory consumption doesn't show up!

This is an issue specific to ARM devices

Dozzle uses the Docker API to gather information about the containers' memory usage. If the memory usage is not showing up, then it is likely that the Docker API is not returning the memory usage.

You can verify this by running docker info, and you should see the following:

WARNING: No memory limit support
WARNING: No swap limit support

In this case, you'll need to add the following line to your /boot/cmdline.txt file and reboot your device.

cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1

License

MIT

Building

To Build and test locally:

1. Install NodeJs and pnpm.
2. Install Go.
3. Install reflex with go get -u github.com/cespare/reflex outside of dozzle.
4. Install node modules pnpm install.
5. Do pnpm dev