[SOLVED] failed to solve with frontend dockerfile.v0

In this article, we have explored the reason behind the error "failed to solve with frontend dockerfile.v0" and presented multiple ways (5) to fix it. This error is related to Buildkit and LLB component of Docker.

Table of contents:

1. The Error: failed to solve with frontend dockerfile.v0
2. Fix 1: Disable Buildkit of Docker
3. Fix 2: Ensure Dockerfile is named correctly
4. Fix 3: Specify filename in docker-compose.yml
5. Fix 4: Delete token seed
6. Fix 5: Disable Buildkit from settings
7. Concluding Note

Following error summarizes the case of this error:

Point	Details on error
Error:	failed to solve with frontend dockerfile.v0
Variants of the error:	failed to compute cache key: "/.env" not found: not found error from sender: context canceled rpc error: code = Unknown desc = failed to parse and more.
Source of error:	Modcache, Buildkit or LLB component in Docker
When error comes?	While building a Docker file
Number of possible fixes	5

The Error: failed to solve with frontend dockerfile.v0

While building a Docker using the following command, you may encounter a specific error that will act as a blocker.

docker build . -t opengenus

Following is the error you may get depending on your environment:

failed to solve with frontend dockerfile.v0: failed to build LLB:
failed to compute cache key: "/.env" not found: not found

OR

failed to solve with frontend dockerfile.v0: failed to build LLB:
error from sender: context canceled

This can be attributed to a known issue with the Modcache or Buildkit in Docker system. There can be other sources of this error and as we have presented multiple solutions.

• LLB stands for Low Level Build and is a binary format that is used internally by Docker. It uses a graph data structure.
• Frontend is the component in Docker that converts the defined Docker build format to LLB.
• The error happens in this step.

Following components are the source of this error:

• Buildkit
• LLB
• Frontend (error occurs in this step)

Fix 1: Disable Buildkit of Docker

Buildkit is a new utility in Docker that replaces the legacy builder. It has a feature to reuse dockerfiles for optimal performance and handle complex situations. It has been observed that the utility does not work well with all legacy docker files and hence, the error will come. The fix is to disable Buildkit using the following two environmental variables:

export DOCKER_BUILDKIT=0
export COMPOSE_DOCKER_CLI_BUILD=0

Following this, try building the Docker again and the error will be fixed:

docker build . -t opengenus

Depending on your system environment, if this fix does not work, move to the next fix. You need not revert back the changes in this fix.

Fix 2: Ensure Dockerfile is named correctly

Make sure that the docker file is named as "Dockerfile" exactly and not as other variants like "DockerFile", "dockerfile" and others.

The docker command fetches this file in a case-sensitive fashion and if it is wrongly named, the docker command is unable to find the setting file and hence, the error may come up.

Fix 3: Specify filename in docker-compose.yml

If the above fix does not work, we may try to specific the Docker file name in docker-compose.yml file to ensure that the Docker picks up the right file overcoming Modcache component.

By default, docker-compose.yml will look as follows:

version: "3"
...
    build:
      context: ../.
      dockerfile: .

It should be updated as:

version: "3"
...
    build:
      context: ../.
      dockerfile: Dockerfile

Notice the last line where the filename is specified.

Fix 4: Delete token seed

If you are using MacOS and you get this error:

failed to solve with frontend dockerfile.v0: failed to create LLB definition: 
rpc error: code = Unknown desc = failed to parse 
/Users/opengenus/.docker/.token_seed: unexpected end of JSON input

The simple fix is to delete the following 2 files in /Users/opengenus/.docker/ directory:

• .token_seed
• .token_seed.lock

This will start a fresh build ignoring the cached components from the previous failed Docker builds.

Fix 5: Disable Buildkit from settings

In Fix 1, we tried to disable Buildkit through environment variables. In some cases, when Docker is used in a Desktop system running Windows or MacOS, we need to disable it from the settings.

Disable buildkit in "Docker Engine" JSON config (in Docker on desktop system). The steps are as follows:

• Open Docker Desktop applications
• Go to Settings
• Go to "Docker Engine"
• Update the true value for buildkit to false in features section.

# Change this line
"features": { buildkit: true}
# to
"features": { buildkit: false}

This should finally fix the error and you can proceed forward building the Docker file.

Concluding Note

Docker is an important tool with several components which may not work well with legacy Docker files. Resolving such errors and proceeding to build Docker files is easy if you find the right fix as presented in this article at OpenGenus.

With this article at OpenGenus, you must have the complete idea of how to solve this Docker error successfully.