Updated April 5, 2023

Terraform module to deploy Bypass Censorship Enterprise Onion Toolkit instances in AWS.

This module supports creating multiple EC2 instances, each serving the same selection of onion services. Due to the way that onion services are published, this provides basic load balancing and failover, although there is no direct coordination between the EOTK instances.

Each EC2 instance is deployed to a separate availability zone (up to a maximum number of the number of available availability zones within the region).

The nginx reverse proxy server configured by EOTK on each instance will keep access logs and these will be rotated hourly. On rotation, the logs will be copied to an S3 bucket for processing by an analytics system.

Rather than replace the EC2 instance on every update, which would be difficult given that EOTK builds tor and OpenResty from source as part of the installation process (time consuming), a script is installed to reconfigure EOTK every 25 minutes with any updated configuration bundle uploaded to the S3 bucket. The EC2 instances should still be considered “disposable” however, as new AMIs will cause EC2 instance replacement.

terraform-aws-bc-eotk overview


Before the module may be used, a zip file containing the EOTK configuration and the necessary Onion and TLS keys and certificates must be created. This may be done with archive_file or with a tool like deterministic-zip if it is acceptable to have a non-Terraform solution for that part. No directory structure is used within the zip file, it has only a flat structure. To begin, create a file named sites.conf that contains your EOTK configuration, for example:

set log_separate 1

set nginx_resolver ipv6=off  # The EC2 instance will have systemd-resolved

set nginx_cache_seconds 60  # Handle bursts, but don't cache anything too long
set nginx_cache_size 64m
set nginx_tmpfile_size 8m

set x_from_onion_value 1

foreignmap facebookwkhpilnemxj7asaniu7vnjjbiltxjqhye3mhbshg7kx5tfyd.onion facebook.com
foreignmap twitter3e4tixl4xyajtrzo62zg5vztmjuricljdp2c5kshju4avyoid.onion twitter.com

set project sites

hardmap systems3hwkxej5nzmo6kvwgx6sik2plqe4w3lsqglr6xhvyi2xlsmqd test.sr2.uk

For each onion service, you’ll need to include 4 more files in the zip file:

  • <onion address without .onion>.v3sec.key - Onion secret key
  • <onion address without .onion>.v3pub.key - Onion public key
  • <first 20 characters of onion address>-v3.pem - TLS private key (PEM encoded)
  • <first 20 characters of onion address>-v3.cert - TLS certificate (PEM encoded)

For the example given above, these files would be named:

  • systems3hwkxej5nzmo6kvwgx6sik2plqe4w3lsqglr6xhvyi2xlsmqd.v3sec.key - Onion secret key
  • systems3hwkxej5nzmo6kvwgx6sik2plqe4w3lsqglr6xhvyi2xlsmqd.v3pub.key - Onion public key
  • systems3hwkxej5nzmo6-v3.cert - TLS private key (PEM encoded)
  • systems3hwkxej5nzmo6-v3.pem - TLS certificate (PEM encoded)

You can then use the module to create EC2 instances and other resources to run EOTK and serve the onion site:

module "eotk" {
  source               = "sr2c/bc-eotk/aws"
  namespace            = "eg"
  name                 = "bc-eotk"
  instance_count       = 1
  configuration_bundle = "configuration.zip"


terraform>= 1.3.0
aws>= 4.4.0
cloudinit>= 2.2.0






aws_ami.ubuntudata source
aws_availability_zones.availabledata source
aws_subnet.defaultdata source
aws_vpc.defaultdata source
cloudinit_config.thisdata 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.
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.
configuration_bundlePath to the zip file that contains the configuration bundle to be uploaded to the configuration bucket.stringn/ayes
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
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).
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.
instance_countNumber of EC2 instances to create. If the number specified is more than the number of available availability zones,
the number of instances will be capped to the number of available availability zones. If the number is zero then no
instances will be created.
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.
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


instancesAn object mapping the availability zone in use to the instance ID for the created EC2 instance running EOTK in that
availability zone.
log_bucket_arnThe ARN of the log bucket created to hold the nginx access logs.
log_bucket_idThe ID of the log bucket created to hold the nginx access logs.
Tags: aws terraform ec2 bypass-censorship tor onion-services eotk