Technical Details¶
easy_infra.yml¶
easy_infra
is a project which makes heavy use of generated code and composable container images. easy_infra.yml
is the centralized
configuration to instruct those generation and composition processes. It describes which version of software to use, where, how to generate the very
important /functions
script (more on that in functions and functions.j2), which is what provides all of the hooking and capabilities.
Here is a ficticious easy_infra.yml
that concisely demonstrates the various features that are possible:
_anchors:
file_extensions: &id001
- tf
security: &id002
checkov:
command: checkov -d . --download-external-modules True --skip-download --output
json --output-file-path ${CHECKOV_JSON_REPORT_PATH}/checkov.json,
customizations:
CHECKOV_BASELINE: --baseline
description: directory scan
validation: &id003
- command: terraform init -backend=false
description: initialization
- command: terraform validate
description: validation
packages:
fluent-bit:
helper: ["all"]
version: v2.0.5
version_argument: --version
checkov:
allow_update: False
version: 2.2.8
version_argument: --version
tfenv:
aliases:
- tfe
allow_filter:
- match: exec
position: 0
file_extensions: *id001
helper: ["terraform"]
security: *id002
validation: *id003
version: v3.0.0
version_argument: --version
Note
Not all of these features are always in use in easy_infra.yml
YAML Anchors and Aliases¶
Anchors and Aliases are a yaml concept, and are fully supported in easy_infra.yml
to support reusable components. See &id001
and *id001
above to see an example. Learn more here and here.
Packages¶
All of the terms under packages
are the names of packages, and the details of how and when they are installed are described in that object of the
easy_infra.yml
. In order to register a runtime hook against a package (Learn more about hooks here), or define what
security scans occur prior to executing, it must be defined under packages
.
Alias¶
Certain tools have multiple ways to run them, such as by running kubectl
or simply k
. These aliases often point to the exact same binary, and
if you’d like to support multiple aliases for a tool, provide a list of those aliases under aliases
in easy_infra.yml
, which will result in
/functions
containing an appropriate function hook for each of the aliases.
Allow filter¶
The allow_filter
allows you to perform security scans only for a very specific sub-command of a given package or alias. For instance, in the above
example, we have:
tfenv:
allow_filter:
- match: exec
position: 0
This ensures that, in the generated tfenv
function in /functions
, it will check for exec
in the 0
position (0-indexed, starting after
the command, and after any easy_infra specific arguments have been removed (i.e. --skip-checkov
)), and only if there’s a match will it continue to
perform security scans as described in the security
object under the respective package
(i.e. tfenv
).
Allow update¶
When projects are added to easy_infra
they are automatically onboarded to our automated maintenance scripts (see def update
in tasks.py
for how that works). All projects that are properly configured will be automatically updated when invoke update
is run, and allow_update
is a
boolean field under that package in easy_infra.yml
which allows the onboarding of a package, while exempting it from automatic updates. This is
typically temporary, and only done when a given project changes how it performs releases or makes a breaking changes that we have yet to accomodate.
File extensions¶
file_extensions
exist to support the AUTODETECT
function. If a package
doesn’t have file extensions defined, the project’s autodetect
logic is unable to detect where files that relate to the command being run exist.
Security¶
The backbone of this project is the security
section. All of the terms underneath security define the series of security tools which will be run
every time the related command is run. An alternative easy_infra.yml
would look something like this:
packages:
checkov:
version: 2.2.8
version_argument: --version
kics:
version: v1.5.1
version_argument: version
tfenv:
aliases:
- tfe
allow_filter:
- match: exec
position: 0
file_extensions:
- .tf
security:
checkov:
command: checkov -d . --download-external-modules True --skip-download --output
json --output-file-path ${CHECKOV_JSON_REPORT_PATH}/checkov.json,
customizations:
CHECKOV_BASELINE: --baseline
CHECKOV_EXTERNAL_CHECKS_DIR: --external-checks-dir
CHECKOV_SKIP_CHECK: --skip-check
description: directory scan
kics:
command: kics scan --type Terraform --no-progress --queries-path ${KICS_INCLUDE_QUERIES_PATH}
--libraries-path ${KICS_LIBRARY_PATH} --report-formats json --output-path
${KICS_JSON_REPORT_PATH} --output-name kics --path .
customizations:
KICS_EXCLUDE_SEVERITIES: --exclude-severities
KICS_INCLUDE_QUERIES: --include-queries
description: directory scan
version: v3.0.0
version_argument: --version
After building easy_infra
with this configuration, you should be able to expect that when you run tfenv exec init
inside of an easy_infra
container,
then it would run both the kics
and checkov
security tools as described under kics: command: ...
and checkov: command: ...
, with additional
customizations as defined under kics: customizations: ...
and checkov: customizations: ...
when the associated environment variables are set.
As an example, if you ran tfenv exec init
and also had the CHECKOV_BASELINE
environment variable set to /iac/.checkov.baseline
then the
actual checkov command that would be run would be:
checkov -d . --download-external-modules True --skip-download --output json --output-file-path ${CHECKOV_JSON_REPORT_PATH}/checkov.json,
--baseline /iac/.checkov.baseline
Note
The --baseline ...
at the end was dynamically added due to the enviornment variable.
Validation¶
Sometimes security scanning tools are only equipped to run against IaC which is in a certain state, such as ensuring that the IaC is formatted properly and
valid. validation
is where you can specify what those are, and you can specify a list of commands to run in the specified order, prior to running the
security scanning tools.
Version¶
version
is where you can specify which versions of tool you want to include when you’re buliding an easy_infra
image. This is what is maintained by this
project’s automated maintenance scripts, and it is parsed into build arguments which are passed into the container image building process.
Version Argument¶
version_argument
is a way for us to describe how a command requests its version inside of easy_infra
. This is useful to know because we avoid running
security scans (and validation, if any is specified) when the version of a tool is being queried inside of an easy_infra
container.
build/¶
All build/Dockerfile*
files must all be able to be built independently, as long as their pre-requisites are met. Typically this means you pass in
the appropriate *_VERSION
build arguments, and you pass in an EASY_INFRA_TAG
build argument that maps to a seiso/easy_infra_base tag locally.
For example, a command like the following should work when run from the build
directory if seiso/easy_infra_base:2022.11.06-terraform-943a052 is
available locally:
docker build -t ansible-test --build-arg ANSIBLE_VERSION=2.9.6+dfsg-1 --build-arg EASY_INFRA_TAG=2022.11.06-terraform-943a052 . -f
Dockerfile.ansible
All build/Dockerfrag*
files cannot be built individually and are only fragments of an image specification. They are meant to be layered on top of
their respective Dockerfile
.
functions and functions.j2¶
functions.j2
is a Jinja2 template, which is rendered into a functions
script, and then copied into each easy_infra
image at build time.
This all works based on the combination of this /functions
file existing inside of the container, commands being run from within a shell (whether
or not you specify bash -c
or not when running a container), and the BASH_ENV
environment variable pointing to /functions
. The way that we
ensure that all commands are run inside a shell is by using "$@"
in the easy_infra
image entrypoint
of docker-entrypoint.sh
.
Because BASH_ENV
will ensure that /functions
is loaded into the shell at initialization, and /functions
contains functions which match the
name of tools which we are protecting, we can use those functions to perform security scans, arbitrary hooks, and logging prior to executing the
original command.
Ultimately, this means that when you run terraform
(or some other properly defined package in easy_infra.yml) inside of easy_infra
, it will
actually run the function “terraform”, which will run the security scans, hooks, and logging, and only after evaluating the precursor logic will it
run command terraform
which runs the terraform
binary from the PATH
.
Internal naming¶
Tool: An executable file in the easy_infra user’s
PATH
which perform IaC actions and has an associated security tool, as described in the easy_infra.yml used when building the image.Security tool: An executable file in the easy_infra user’s
PATH
which is configured to perform a security scan for an associated “tool” (see above), as configured in theeasy_infra.yml
file used to build the image.Package: The name of a package that can be installed to perform a necessary function. It could be a tool, a security tool, or a generic helper such as
fluent-bit
orenvconsul
.Command: A runtime command, following the use of the term by bash (see the “Command Execution” of this documentation). This could be an alias, a package, or some other executable on the user’s
PATH
.Alias: An executable file in the easy_infra user’s
PATH
which executes the installed by a package. Whileaws-cli
would be a package,aws
would be the associated alias.Environment: A supported destination that a tool (see above) may deploy into, such as a cloud provider. An environment constitutes a bundle of packages.
High-Level Design of the image build process¶
When building the easy_infra
images, the high level design is that files in the build/
directory are composed together using tasks.py
to
create multiple final container images for various use cases. Those use cases are primarily based around the use of an IaC “tool” (i.e. terraform
or ansible
), and an associated set of “security tools” (i.e. checkov
or kics
) which will run transparently when the IaC tool is used
inside of a container. There are also sometimes optional “environment” (i.e. aws
or azure
) images which add environment-specific helpers or
tools, based on the tool that the image focuses on.
There are two general types of files in build/
; Dockerfile*
and Dockerfrag*
.
All Dockerfile*
files should be able to be built and tested independently, and are effectively the “install” step of building the easy_infra
images. It is possible that an easy_infra
Dockerfile
may only contain a FROM
statement, if we are using a container built and distributed
by the upstream project. Dockerfile
suffixes MUST also be the same as a given package
as outlined in the easy_infra.yml
(aliases are not
supported), with the single exception of Dockerfile.base
(for example, the terraform
package’s Dockerfile
must be
Dockerfile.terraform
).
All Dockerfrag*
files should not be built and tested independently, as they are solely fragments which depend on the related Dockerfile
. For
instance, Dockerfrag.terraform
is meant to build on top of Dockerfile.terraform
. The contents of a Dockerfrag
often hinge around running
COPY
commands to pull files from the Dockerfile
. This model allows us to create extremely minimal final images with limited bloat and
consideration of extraneous packages or dependencies which are only needed at build time.
In order for a Dockerfile
and a Dockerfrag
to be “linked” together, they must share the same suffix. For example, Dockerfrag.abc
should
build on top of Dockerfile.abc
, and it is both expected that in Dockerfrag.abc
it copies files using COPY --from=abc ...
, and that in
Dockerfile.abc
the FROM
statement ends with ... as abc
.
Adding to the project¶
Adding a tool¶
Add the package to
easy-infra.yml
underpackages
and include a validsecurity
,file_extensions
,version
, andversion_argument
section. Consider other optional configurations as they apply (see easy_infra.yml for more details).Modify
docker-entrypoint.sh
to print the tool version if the correct binary exists inside of the container.Create a
Dockerfile.{tool}
andDockerfrag.{tool}
in thebuild/
directory.You may need to add the tool name or any aliases in
.github/etc/dictionary.txt
if it is not a standard english word, assuming it is used in documentation.Create a new folder in
docs/
and add documentation regarding the tool. Reference the new docs in thetoctree
ofdocs/index.rst
in line with the othertoctree
entries.Consider developing any specialized hooks, using the hooks framework.
Write tests in
tests/test.py
by creating a new function namedrun_{tool}
and following the pattern that otherrun_*
functions follow by creating a list of 3-tuple tests, and then using theexec_tests
function to perform the tests and return the number of tests that were successfully run, logging the amount and type of tests performed at the end of the function.Add a folder under
tests/
aligned to the tool name, and create a variety of different configuration files that will be referenced by the tests intests/test.py
. Ensure that there are:invalid
andsecure
folders containing aligned configuration files, typically undertests/{tool}/general/
.At least one
security_tool/{security_tool}
folder undertests/{tool}
containing insecure code.If you developed hooks which register to the tool, create a
tests/{tool}/hooks/
directory, containing a variety of folders that exercise those built-in hooks.
Identify how the latest released version of the tool (the “package”) can be retrieved. Ensure that the
update
function intasks.py
will retrieve the latest version appropriately. You may be able to use some of the existing mechanisms (such as usingapt
, github repo releases, github repo tags, python package versions, etc.) which are maintained ineasy_infra/constants.py
and whose update functions exist ineasy_infra/utils.py
(see theget_latest_release_from_*
functions).
Note
If you need any special configuration at build time specific to the combination of a tool and an environment, you can create a
Dockerfile.{tool}-{environment}
and Dockerfrag.{tool}-{environment}
. These are entirely optional.