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Component: bastion

This component is responsible for provisioning a generic Bastion host within an ASG with parameterized user_data and support for AWS SSM Session Manager for remote access with IAM authentication.

If a special script is desired to run, set container_enabled to true, and set the image_repository and image_container variables.

By default, this component acts as an "SSM Bastion", which is deployed to a private subnet and has SSM Enabled, allowing access via the AWS Console, AWS CLI, or SSM Session tools such as aws-gate. Alternatively, this component can be used as a regular SSH Bastion, deployed to a public subnet with Security Group Rules allowing inbound traffic over port 22.


Stack Level: Regional

By default, this component can be used as an "SSM Bastion" (deployed to a private subnet, accessed via SSM):

enabled: true
name: bastion-ssm
instance_type: t3.micro
image_container: infrastructure:latest
image_repository: ""

The following is an example snippet for how to use this component as a traditional bastion:

enabled: true
name: bastion-traditional
image_container: infrastructure:latest
image_repository: ""
associate_public_ip_address: true # deploy to public subnet and associate public IP with instance
custom_bastion_hostname: bastion
- type : "ingress"
from_port : 22
to_port : 22
protocol : tcp
cidr_blocks : [""]
- type : "egress"
from_port : 0
to_port : 0
protocol : -1
cidr_blocks : [""]


terraform>= 1.0.0
aws>= 4.0
cloudinit>= 2.2


aws>= 4.0
cloudinit>= 2.2




aws_ami.bastion_imagedata source
aws_iam_policy_document.defaultdata source
aws_iam_policy_document.maindata source
cloudinit_config.configdata source


additional_tag_mapAdditional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.
associate_public_ip_addressWhether to associate public IP to the instance.boolfalseno
attributesID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.
container_commandThe container command passed in after docker run --rm -it <image> bash -c.string"bash"no
contextSingle object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.
"additional_tag_map": {},
"attributes": [],
"delimiter": null,
"descriptor_formats": {},
"enabled": true,
"environment": null,
"id_length_limit": null,
"label_key_case": null,
"label_order": [],
"label_value_case": null,
"labels_as_tags": [
"name": null,
"namespace": null,
"regex_replace_chars": null,
"stage": null,
"tags": {},
"tenant": null
custom_bastion_hostnameHostname to assign with bastion instancestringnullno
delimiterDelimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.
descriptor_formatsDescribe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
{<br/> format = string<br/> labels = list(string)<br/>}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).
ebs_block_device_volume_sizeThe volume size (in GiB) to provision for the EBS block device. Creation skipped if size is 0number0no
ebs_delete_on_terminationWhether the EBS volume should be destroyed on instance terminationboolfalseno
enabledSet to false to prevent the module from creating any resourcesboolnullno
environmentID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'stringnullno
id_length_limitLimit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.
image_containerThe image container to use in""no
image_repositoryThe image repository to use in""no
import_profile_nameAWS Profile name to use when importing a resourcestringnullno
import_role_arnIAM Role ARN to use when importing a resourcestringnullno
instance_typeBastion instance typestring"t2.micro"no
kms_alias_name_ssmKMS alias name for SSMstring"alias/aws/ssm"no
label_key_caseControls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.
label_orderThe order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.
label_value_caseControls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.
labels_as_tagsSet of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.
nameID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.
namespaceID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally uniquestringnullno
regex_replace_charsTerraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.
regionAWS regionstringn/ayes
root_block_device_volume_sizeThe volume size (in GiB) to provision for the root block device. It cannot be smaller than the AMI it refers to.number8no
security_group_rulesA list of maps of Security Group rules.
The values of map is fully complated with aws_security_group_rule resource.
To get more info see .
"cidr_blocks": [
"from_port": 0,
"protocol": -1,
"to_port": 0,
"type": "egress"
"cidr_blocks": [
"from_port": 22,
"protocol": "tcp",
"to_port": 22,
"type": "ingress"
stageID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'stringnullno
tagsAdditional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.
tenantID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is forstringnullno
user_dataUser data contentlist(string)[]no
vanity_domainVanity domainstringnullno


autoscaling_group_idThe AutoScaling Group ID
iam_instance_profileName of AWS IAM Instance Profile
security_group_idID on the AWS Security Group associated with the ASG