docker history

Show the history of an image

Prerequisites

• Docker

  Docker is a tool to build safer, share wider, run faster: New updates to our product subscriptions.

  See Empowering App Development for Developers | Docker - https://www.docker.com/
  to learn more.

Usage

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$ docker history [OPTIONS] IMAGE

For example uses of this command, refer to the examples section below.

Options

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Name, shorthand	Default	Description
--format		Pretty-print images using a Go template
--human , -H	true	Print sizes and dates in human readable format
--no-trunc		Don't truncate output
--quiet , -q		Only show image IDs

Examples

To see how the docker:latest image was built:

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$ docker history docker
(nop) ENV LC_ALL=C.UTF-8            0 B
(nop) ADD jessie.tar.xz in /        121 MB
(nop) MAINTAINER Tianon Gravi <ad   0 B

To see how the docker:apache image was added to a container’s base image:

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$ docker history docker:scm
(nop) ADD file:1fd8d7f9f6557cafc7   373.7 MB
(nop) MAINTAINER Lokesh Mandvekar   0 B

Format the output

The formatting option (--format) will pretty-prints history output using a Go template.

Valid placeholders for the Go template are listed below:

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Placeholder	Description
.ID	Image ID
.CreatedSince	Elapsed time since the image was created if --human=true, otherwise timestamp of when image was created
.CreatedAt	Timestamp of when image was created
.CreatedBy	Command that was used to create the image
.Size	Image disk size
.Comment	Comment for image

When using the --format option, the history command will either output the data exactly as the template declares or, when using the table directive, will include column headers as well.

The following example uses a template without headers and outputs the ID and CreatedSince entries separated by a colon (:) for the busybox image:

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$ docker history --format "{{.ID}}: {{.CreatedSince}}" busybox
: 4 weeks ago

References

[1] docker history | Docker Documentation - https://docs.docker.com/engine/reference/commandline/history/

[2] Empowering App Development for Developers | Docker - https://www.docker.com/

Nginx Header Security

Here’s how to add various HTTP response header to your Nginx site for better website security protection.

errors

error is a interface, here is its definition:

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type error interface {
    Error() string
}

redis-rb

A Ruby client that tries to match Redis’ API one-to-one, while still providing an idiomatic interface.

Diagrams

Diagrams lets you draw the cloud system architecture in Python code.

It was born for prototyping a new system architecture without any design tools. You can also describe or visualize the existing system architecture as well.

Paramiko

Paramiko is a pure-Python (2.7, 3.4+) implementation of the SSHv2 protocol, providing both client and server functionality. It provides the foundation for the high-level SSH library Fabric, which is what we recommend you use for common client use-cases such as running remote shell commands or transferring files.

Direct use of Paramiko itself is only intended for users who need advanced/low-level primitives or want to run an in-Python sshd.

redis_hash_store

RedisHashStore extends ActiveSupport’s RedisCacheStore - https://github.com/rails/rails/blob/master/activesupport/lib/active_support/cache/redis_cache_store.rb to provide the ability to easily use Redis hashes for caching.

We decided to create this gem because:

• Previously using #delete_matched - https://apidock.com/rails/ActiveSupport/Cache/Store/delete_matched which can have many performance issues at scale (See this similar issue at GitLab - https://gitlab.com/gitlab-org/gitlab/-/issues/201808).

• #deleted_matched doesn’t delete values from all the nodes in a Redis cluster.

Redis Cache Store

The Redis cache store takes advantage of Redis support for automatic eviction when it reaches max memory, allowing it to behave much like a Memcached cache server.

npm FAQs

npm ERR! no space left on device

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$ echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p

npm ERR! No Space left on device · Issue #1131 · npm/npm - https://github.com/npm/npm/issues/1131

Remove macOS FileSystem watch limit. SEE: https://github.com/guard/listen/wiki/Increasing-the-amount-of-inotify-watchers - https://gist.github.com/derekclair/25088e09d2d7147045485ddf8fd165b8

References

[1] [npm/npm: This repository is moving to: https://github.com/npm/cli - https://github.com/npm/npm(https://github.com/npm/npm)]

[2] npm community portal - https://npm.community/

[3] npm - https://www.npmjs.com/

benchmark-ips

An iterations per second enhancement to Benchmark.

FEATURES/PROBLEMS:

benchmark/ips - benchmarks a blocks iterations/second. For short snippits of code, ips automatically figures out how many times to run the code to get interesting data. No more guessing at random iteration counts!