add lots and lots of doc

README.md

@@ -1,4 +1,100 @@
-(will be) a lambda function to convert a tar-gzipped set of pnm files into one OCRed PDF
+Lambda function to convert a tar-gzipped set of pnm files into one OCRed PDF
+
+# Install
+
+## S3 buckets
+
+You need to create:
+
+- one source s3 bucket: this is where you'll upload `tar.gz` files which contains scanned images (only tested with pnm files so far)
+- one destination bucket: this is where this lambda function will upload the resulting pdf to
+
+Both buckets should be in the same region as your lambda function.
+
+## IAM role
+
+Now, create an IAM role which allows to read/write from both source and destination bucket:
+
+1. navigate to IAM
+2. create a **Policy**, switch to JSON tab
+3. put the json below, replace the Resource with the ARNs from the buckets you just created:
+
+	```json
+	{
+	  "Version": "2012-10-17",
+	  "Statement": [
+	    {
+	      "Effect": "Allow",
+	      "Action": ["s3:ListBucket"],
+	      "Resource": ["arn:aws:s3:::<source-bucket>", "arn:aws:s3:::<dest-bucket>"]
+	    },
+	    {
+	      "Effect": "Allow",
+	      "Action": [
+	        "s3:PutObject",
+	        "s3:GetObject",
+	        "s3:DeleteObject"
+	      ],
+	      "Resource": ["arn:aws:s3:::<source-bucket>", "arn:aws:s3:::<dest-bucket>"]
+	    }
+	  ]
+	}
+	```
+4. name the policy e.g. `ReadWriteOCR`
+5. create a **Role** for Lambda
+6. in the permissions step, choose the policy `ReadWriteOCR` you just created
+7. name the role e.g. `ReadWriteOCR`
+
+
+## Lambda function
+
+Set up a lambda function with
+
+- `Name`: e.g. `ocr`
+- `Runtime`: `Python 3.6`
+- `Role`: `Choose an existing role`
+- `Existing role`: the role you just created, e.g. `ReadWriteOCR`
+
+Then, in the lambda function set
+
+- Handler: `handler.handler`
+- env variable: `S3_BUCKET=<bucket-name>` # bucket name where lambda will upload the pdf
+- `Timeout`: 5 minutes
+- Execution role: tbd
+
+Then, populate the function with the prebuilt binary (To build this see below under `Build tesseract binaries`)
+
+- Code entry type: `upload from S3`
+- `S3 link URL`: `s3://hansaplast-share/ocr-lambda.zip` (take the prebuilt lambda from this repo. 
+
+# Test
+
+Upload tar.gz with 1 or more pnm files into `<bucket-name>`. then add new test handler with this:
+
+```json
+{
+  "Records": [
+    {
+      "s3": {
+        "bucket": {
+          "name": "<source-bucket>"
+        },
+        "object": {
+          "key": "<filename-you-just-uploaded>.tar.gz"
+        }
+      }
+    }
+  ]
+}
+```
+
+## Add trigger
+
+From the `Add triggers` menu on the left choose `S3`, then in `Configure trigger` dialogue:
+
+- `Bucket`: the bucket where the lambda function should listen to
+- `Event tpye`: `Object Created (All)`
+- `Prefix` and `Suffix` you can leave empty
 
 # Local testing
 
@@ -9,25 +105,71 @@ export S3_BUCKET=scanner-upload
 echo '{"Records":[{"s3":{"bucket":{"name":"scanner-upload"},"object":{"key":"scan_2018-01-20_155119.tar.gz"}}}]}' | emulambda handler.handler - -v
 ```
 
-# Setup of lambda
+# Build tesseract binaries
 
-- add env variable: `S3_BUCKET=scanner-upload`
-- put `Timeout` to 5 minutes
+This was mainly taken from  [this post](https://stackoverflow.com/questions/33588262/tesseract-ocr-on-aws-lambda-via-virtualenv) with minor modifications.
 
-# Deploying
+Tested, 2018-01-22 on an amazon linux ami 4.9.76-3.78.amzn1.x86_64:
 
-```
-zip -r -q ocr-lambda.zip .
-aws s3 cp ocr-lambda.zip s3://hansaplast-home/
+```bash
+sudo yum install gcc gcc-c++ make -y
+sudo yum install autoconf aclocal automake -y
+sudo yum install libtool -y
+sudo yum install libjpeg-devel libpng-devel libpng-devel libtiff-devel zlib-devel -y
+cd ~
+mkdir leptonica
+cd leptonica/
+wget http://www.leptonica.com/source/leptonica-1.73.tar.gz
+tar -xzvf leptonica-1.73.tar.gz
+cd leptonica-1.73
+./configure
+make
+sudo make install
+cd ~
+mkdir tesseract
+cd tesseract/
+wget https://github.com/tesseract-ocr/tesseract/archive/3.04.01.tar.gz
+tar -xzvf 3.04.01.tar.gz
+cd tesseract-3.04.01/
+./autogen.sh
+./configure
+make
+sudo make install
+cd /usr/local/share/tessdata/
+sudo wget https://github.com/tesseract-ocr/tessdata/raw/3.04.00/eng.traineddata
+sudo wget https://github.com/tesseract-ocr/tessdata/raw/3.04.00/deu.traineddata
+export TESSDATA_PREFIX=/usr/local/share/
+cd ~
+mkdir tesseract-lambda
+cd tesseract-lambda/
+cp /usr/local/bin/tesseract .
+mkdir lib
+cd lib/
+cp /usr/local/lib/libtesseract.so.3 .
+cp /usr/local/lib/liblept.so.5 .
+cp /usr/lib64/libpng12.so.0 .
+cp /usr/lib64/libz.so .
+cd ..
+cp -r /usr/local/share/tessdata .
+cd tessdata
+wget https://github.com/tesseract-ocr/tessdata/raw/master/osd.traineddata
+cd ~
+zip -r tesseract-lambda.zip tesseract-lambda
 ```
 
-On lambda: 
+# Build lambda function
 
-- Code entry type: `upload from S3`
-- Runtime: `Python 3.6`
-- Handler: `handler.handler`
-- `S3 link URL`: `https://s3.eu-central-1.amazonaws.com/hansaplast-home/ocr-lambda.zip`
+Unzip `tesseract-lambda.zip` you just built into the root of this repo
 
-# Build tesseract binaries
+Then upload it to s3:
 
-Note to self: To build this, mainly follow [this post](https://stackoverflow.com/questions/33588262/tesseract-ocr-on-aws-lambda-via-virtualenv), tbd: try to use tesseract 4.0
+```
+zip -r -q ocr-lambda.zip . -x deploy.sh -x ocr-lambda.zip -x README.md
+aws s3 cp ocr-lambda.zip s3://<s3-bucket>/
+```
+
+# Refresh lambda function
+
+```
+aws lambda update-function-code --function-name <lamba-nam> --s3-bucket <s3-bucket> --s3-key ocr-lambda.zip
+```