ERB did not find expected comment or line break while scanning a block scalar-CodePudding

I've an ERB template in YAML file which is parsed successfully and looks like so

---
name: message_from_json_to_raw
config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract'
    end %>
    <%= output %>

I want the output variable to contain | extract at the end irrespective of the if block execution. So I tried the following approaches

config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n")'
    end %>
    <%= output.concat(" | extract ") %>

config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract '
    else 
      output << ' | extract '
    end %>
    <%= output %>

config:
  definition: <% 
    output = ' | extract '
    if "splunk_index".eql? env_index
      output = ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n")'
    end %>
    <%= output %>

config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n")'
    end %>
    <% output.concat(' | extract ') %>
    <%= output %>

config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n")'
    end 
    output << ' | extract ' %>
    <%= output %>

All the above approaches given a single error which looks as follows

/var/lib/spork/.rvm/rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:377:in `parse': (<unknown>): did not find expected comment or line break while scanning a block scalar at line 5 column 6 (Psych::SyntaxError)
    from /var/lib/spork/.rvm/rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:377:in `parse_stream'
    from /var/lib/spork/.rvm/rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:325:in `parse'
    from /var/lib/spork/.rvm/rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:291:in `safe_load'

Any suggestion on what's causing this and a possible fix? This looks similar to the issue here but the suggestions don't look related to this situation.

Interestingly, all of the things I tried work perfectly fine when I use the Ruby REPL here. For instance the below one

require 'erb'

ibus_index = 'ibus_cloud'
template = ERB.new <<-EOF
  <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n")'
    end %>
    <% output.concat(' | extract ') %>
    <%= output %>
EOF
puts template.result(binding)

CodePudding user response：

It seems like the error is telling you the truth: you're missing a line break after your block scalar.

| extract needs to be followed by a line break before the end of the file or the next key.

The reason that the heredoc example worked is because a heredoc is always terminated by a linebreak unless you add chomp.

CodePudding user response：

Let's narrow it down to where the error actually is. Let's render your first example:

# config.yml.erb

---
name: message_from_json_to_raw
config:
  definition: <% 
    output = ''
    if "splunk_index".eql? env_index
      output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract'
    end %>
    <%= output %>

Render erb first. No issues.

>> env_index = "splunk_index"
>> yaml = ERB.new(File.read('config.yml.erb')).result(binding)
>> puts yaml
---
name: message_from_json_to_raw
config:
  definition:
     | spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract

Now it's a plain yaml. This is what's being parsed by Psych

>> Psych.load(yaml)
/home/alex/.rbenv/versions/3.1.1/lib/ruby/3.1.0/psych.rb:455:in `parse': (<unknown>): 
 did not find expected comment or line break while scanning a block scalar
 at line 5 column 6 (Psych::SyntaxError)

This is exact same error you're getting. Line 5 Column 6:

1---
2name: message_from_json_to_raw
3config:
4  definition:
5    |*spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract
 123456

* Gotta have a new line there or have another properly defined block scalar.

Let's untangle the erb a bit to be clear where the output is:

<% 
  output = ''
  if "splunk_index".eql? env_index
    output << ' | spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract'
  end
  # build the output here
%>
---
name: message_from_json_to_raw
config:
  definition: |-
    <%= output %>

|- now a block scalar has a new line, a dash is to remove some extra new lines at the end

It parses into this. I don't know if that's the output you're looking for, but, there is no error.

---
name: message_from_json_to_raw
config:
  definition: '| spath output=_raw path=msg | eval _raw = split(_raw,"\n") | extract'